Annals of Library Science and Documentation 1992,39(1),1-8

IS HYPERTEXT A MORE FLEXIBLETEACHING TOOL FOR EDUCATION?

Hypertext (HT):S nonlinear and nonsequentialtext. The paper gives a brief over view of HT, itsdefinition and salient features. It also describeswhy HT is required for teaching and what are itsstrengths and weeknesses for using it as a teachingtool in education. It also points out the importantreasons for using HT as teaching (001 and itsimpact on education.

INTRODUCTION

Human thinking is not sequential, though itbecomes sequential when it is written for aspeech. Since the birth of paper and book,the literature has been recorded in sequentialand linear fashion and this practice is stillcontinuing today. In reality, there are manycognitive lines between topics and subjects,because the entire Universe of knowledge isinter-linked and inter-related. Hypertext (HT)is nonsequential text, which offers thepossibility of representing and exploringknowledge more originally and naturally.

There are about 100 different types of HT/Hypermedia (~M) systems developed by dif-ferent people for various purposes. Atpresent about a dozen of organisations/institutions/universities are working full time indeveloping such systems. HT is one of thosesoftwares, through which one can developcourseware from kinder garden to advancedresearch. It has got a lot of potentialitieswhich any good teaching technique musthave. Therefore, a number of schools, col-leges and universities have already startedusing it for designing their courseware,presentation of information and developingboth interactive video and computerbased instructions.

HYPERTEXT AND HYPERMEDIA

CKRAMAIAHDESIDOCMinistry of DefenceMetcalfe HouseDelhi-110054

Dr. Vannevar Bush, when he was working asScience Adviser to Roosevelt, President of theUSA, in 1945. During those days he foresawthe problem of future infotmation explosionand developed a mechanical recording de-vice, which he called 'Memax' to cope with hisown information needs.

Afterwords. in 1950s, Douglas C. Engelbart, apioneer in computer science picked up thesame idea and developed a system called'Online System (NLS)' with all those features.He also invented the mouse and five keychord input devices and many more thingsrelated to HT.

The third pillar of HT is Theodor H. Nelson,a computer guru who first coined the word'Hypertext' in 1965 [2] and also many otherwords and new concepts related to this field.It may be that Bush is the originator, Engalbartis the developer, and Nelson the dissemina--torof the idea to the world. Nelson defined HTas follows:

"HT is the combination of natural-languagetext with the computer's capacities forinteractive, branching or dynamic dispiay .of a nonlinear text...... ... which cannot beprinted conveniently on a conventionalpage " [3].

This lead to the modern definition of HT astollows:

"A large number of information fragments/chunks (such as text, graphics and images)linked together electronically forming a multi-faceted indefinite shaped database in whichone can write and read the information non-sequentialy and nonlinearly".

Hypermedia (HM) is simply an extension of HTThe concept of Hypertext was originated by with which authors can create a linked

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corpus of materials that includes text, staticgraphics, animated graphics, video, sound,music, etc. [4]. The difference between HTand HM is that an HT system allows authors tolink together onty textual information blocks,whereas an HM system provides linking capa-bilities between heterogeneous blocks of in-formation created with different applications.So HM is a frame work for nonlinear represen-tation of text, graphics, images, sound andanimation in the computer.

PRINT MEDIA vs HYPERTEXT

In spite of many disadvantages of papermedia for structuring text, its use has contin-ued for the past seven centuries. It is, ofcourse, very convenient and one can placeall the books, periodicals, reports, notes,and other forms of information sources onthe same table and read, compare and workwith them. Whereas with other media likeaudio, video, magnetic and optical media, it isyet not possible to store heterogeneousformats of information on one platform/base,and even if it is possible, comparing would notbe so convenient as in the case of print media.Perhaps easy to use, store, read etc. are verystrong advantages of the paper media be-cause of which it was not replaced by anyother media for a long time.

Many HT systems differ from their print ver-sions on paper in many ways including itsstructure, organization and functionality.Reading full text in HT is much slower thanprinted version but other advantages likeinteractiveness, browsing, navigation througha great volume of text must be set againstits disadvantages. In print version also, onecan create HT features in a document bycreating nodes in the linear text, but this is notas effective as in the electronic form. BenShneiderman's 'Hypertext hands-on! an in-troduction to a new way of organising andaccessing information' is an example for boththe print and the computer version of thebook in HT format. There are two and aquarter inches disks coming with it whichcontain Hyper TIES (a n HT system) version ofthat book. Print version of the book is notfound as affective as the computer version.

Browsing is an important aspect of informa-tion search even in electronic environment.

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There are a number of effective browsingtechniques in HT, but the prominent onesrange from random and informal to system-atic and formal. Since HT is always dynamic,the organization of a document is such thatthe reader is not at all limited by only nodesbut there are also so many other advantages.HM/HT system allows users to browse andnavigate quickly through any complex net-works of information, and find explanations,references, comparisons, definitions etc. fromthe nodal points created in the system whichgives a HT a considerable potential in devel-oping and using the courseware for the stu-dents.

SALIENT FEATURES OF HYPERTEXT

In HT, knowledge (information) is repre-sented in frames (Knowledge ManagementSystems or KMS), cards (Hypercards,Notecards), nodes, i.e. Geographical IssueBased Information Systems (GIBIS), etc. Theinformation may be a paragraph, a diagram,a graphic or a combination of any of theseitems. By inter-linking all the small chunks/fragments of information, a HT database isformed.

Following are the salient features of a HT data-base.

- Users can rapidly navigate within a HTdatabase, moving from one chunk to an-other by selecting/clicking on them is easy.

A user can create, edit and rearrange thechunks according to his interest and needs.

- The user is able to see even a small frag-ment of information at any time even in alarge HT database.

- In HT, there are no hierarchical pageboundaries like a conventional book.

- In a HT systems, the user can navigate bymoving rapidly in either direction betweenthe nodes of the HT database.

- In a HT environment, the computer bringsthe user close to natural human knowl-edge processing. Even though HT doesnot incorporate an artificial intelligence (AI)concept like an Expert System (ES), it is

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HYPER TEXT· A TEACHING TOOL

more useful than the ES in enhancinghuman skills and knowledge effectively.

- A n HT system allows the user to accessinformation by both associative and intui-tive routes, irrespective of knowledge of theactual location of information or any visibledatabase structure.

- To a large extent, HT leaves c-ontrol of infor-mation in the hands of users.

- The HT database can have a changeablestructure ( like an amoeba) It keeps onchanging according to the author(s) ordesigner(s) addition, deletion or editing ofthe text, graphics, images, etc. It does nothave a clear structure like a conventionalbook in which the length and breadth can bedefined. Moreover the arrangement of in-formation in the HT database Changesevery time according to the user's interac-tion.

- In HT environment, there is no differencebetween author and reader or teacher andstudent. All are equal.

- Unlike a printed book, HT is multifaced withmany entry points to add or retrieveinformation according to the need/re-quirement, level of interest and learningstyle of the user population.

HYPERTEXT AS A TEACHING TOOL

Use of movies, audio-visual (A-V) materialslike transparencies, slides, audio tapes, etc.,and Computer-Aided Instructional (CAI)materials was initialy introduced in theeducational technology to supplement thetraditional teaching methods. But none ofthem replaced the conventional teachingmethods. The teaching aids changed theposition of the instructor from teacher to helper.Almost a revolution took place in the field ofeducational technology when videos andcomputers were introduced as teaching aids/tools for teaching in the schools, colleges anduniversities. The educationists started devel-oping their lessons in the form of video tapesand CAI programs in which students couldlisten, watch and interact with the coursematerial. When using it, if a student could notunderstand a particular concept, he/she

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could replay that part as many times as re-quired and clear the doubts.

In the 1970s and 1980s, a number of newteaching tools/methods were introduced suchas Expert systems Interactive Video Disc(IVD), Computer Aided Learning (CAL),Computer Based Training (CBT), Multimediaand the recent HT. HT has got powerfulinteractive methods. It is very simple and fastin retrieving associated information from thedatabase. HM has gone a step further byincorporating other media elements to text. Itis one of the most important recent innova-tions in the field of educational technologyand has made a lot of impact on students intheir learning processes. Because of its non-linear writing and inter-linking of informationfragments, called 'seamless information',itprovides random access to a piece of informa-tion in a database. A major problem is thatboth HT and HM require good data modellingto interlink the data files, The beauty of HT forteaching is customizing and developing per-sonal links inbetween the information frag-ments in a hypertext database.

REVIEW OF LITERATURE ON USE OF HT

HT has got lot of potential and flexibility in theways of presenting the teaching materials.The students may change it as they want andunderstand fully. Moreover, as compared toother teaching tools, it is easier to experimentand reorganize the information in the read-ing materials. HT offers innumerable possi-bilities for teaching and learning to both thestudents and the teachers of any subject.Research on this topic suggests that HTcultivated among the students, the habit ofcritical thinking, skilled reading and logicallinking of related fragments of information [5].It is a good tool for the students because theycan assimilate a large portion of informationwhile reading and developing links. Thus it isnot only possible to use HT to present thebasic informtion on a subject,' but also toencourage analytical thinking about the pres-entation and linking of that information. Thecapacity to allow multiple links to an individualchunk of information may encourage thestudents to cultivate the habit of approachingany information fragment from multiple direc-tions and thinking critically to add their com-ments. Moreover it makes the students par-

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ticipate in the teaching and learning programrather than the passive type of learning intraditional teaching.

In an HT environment, when a student is givena selected list of readings (hypertext course-ware materials) for doing an assignment, nor-mally without going through all those mate-rials, the student cannot complete the as-signment satisfactorily. Whereas in tradi-tional teaching, the students may do selectivereadings for completing their assignments orcoursework, with the result that the studentsare not reading even the prescribed syllabus.As a result they do not understand the subjectfully, which ultimately effects the basic pur-pose of education. This is one of thestrongest factors of HT which achieves one ofthe main objectives of education, which otherCBT systems or A-V tools could not achievefrom ages together.

Another advantage of HT is that duringlearning process the student developsauthoring skills and also start contributing hisviews as notes, new thoughts, arguments,comments, etc. which ultimately affects thegrowth of HT system. The student may feelmore responsible because his contributionswill be referred to by other students and teach-ers. This does not only help the students inestablishing a communication link betweenthe le5!rning community of the system but alsoprovides them chance to present their ideas.HT has got multifaced instructional applica-tions in all areas of curriculum. The teacherswould have an infinitelygreater range of choiceover what to teach. Many instructors indifferent schools, colleges and universitieshave started developing HT systems forteaching.

Brown University's English and Biology de-partments were the first to use the hypertextfor teaching at the University level and foundthat the students who used these materialswere not only quick to grasp the subject, butalso developed analytical thinking anddesigning skills [6]. So during the teachingprocess, HT as a teaching tool reflects onstudents' thinking and improves their meta-cognitive skills.

In the University of Southern California it wasobserved that the students of Freshman

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Writing Program "Project Jefferson" felt diffi-culty in accessing information in the libraryfor their composition class which resulted inpoor quality of tL...eirresearch papers. Toovercome this problem, Clark started the'Project Jefferson' using Hypercard for teach-ing the fundamental research skills like howtoget information and utilize it for their aca-demic writing. Eventually, she found that HTmade profound impact on the students inimproving their academic writing [7). Kay E.Vandergriff of the State University of NewJersey has selected Edna St. Vincent Millay'spoem "Justice Denied in Masschussets" anddesigned a Hypercard stack for teaching. SincePoetry is the neglected area in the literature,he took a poem as an example and experi-mented in developing a Hypercard course-ware for teaching his students. He also sug-gested the librarians to build the stackwarecollection in the libraries and the ways toovercome the copyright problems but has notreported the impact of that courseware on thestudents [8).

A number of departments at the University ofToledo, such as Department of EducationalTechnology, Biology, Foreign Languages andsome others are developing their coursewarein the form of Computer-Based Instructionalmaterials and Interactive video programmesusing Hypercard software. The response ofthe students seems to be noticeable [9).

In a class, after some exposure to the system,the students were observed to develop thestories on art education and needed a littleintervention by the tutor to guide them in ex-tending their abilities [10]. They liked tosubmit their assignments in hypertext formrather than traditional form.

At Wayne State University, John Camp andMare Cogan have developed "The School ofAthens", a stackware for the art students withthe help of Hypercard. The art lessons in theform of stackware influenced the students'participation and created interest in teachingto a great extent [11].

At Coventry Polytechnic, Alan Dyer has inves-tigated a number of problems related to HTand art & design teaching. They found that thestudents' creative capabilities were expand-ing after using the HT courseware both in

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HYPER TEXT· A TEACHING TOOL

theoretical studies and studio design work[12).

The most interesting observation was thatseveral students were enthusiastic in submit-ting their assignments (i.e. essays, thesis,etc.) in the form of HT documents. The depart-ment is now investigating the impact i.e.special cognitive skills and educational benefitsof HT on the students while authoring theircourse work.

"The Living Textbook of Pathology" is aninteractive HT system developed to providea framework for interactive growth and updat-ing of an under graduate pathology curricu-lum. The living text system utilizes a mata-base which is a database about the data-bases. This system consists of various typesinformation like what type of users, how andwhere, can get and save the information,and who is (are) the author (s) of those infor-mation fragments, etc. A number of importantlessons were developed on this system andthe use of the system by the students wasalso recorded, which was very significant i.e.3600 hours for all lessons. At that time theycould not measure or find any direct impacton the undergraduate medical studentsbecause of its prototypeness, but found itsusefulness for the continuing education ofpracticing physicians, even at the beginningof its development [13).

"Training the Trainers", an HT based trainingpackage was designed by Philip J. Gart-shore, school of Architecture, PortsmouthPolytechnic to study various methods of stu-dents learning. The package was designedwith HyperCard software and implementedon an IVD. It was also found that this trainingpackage motivated the students in using itmore and more [14).

In 1989, Drexel University has developedHyperCard based HT instructional sottv.••aretool called 'Drexel Disk' for distributing theday-to-day required basic information aboutthe University, its departments and facilitiesavailable to all the newly joined students. Theyfound that the distribution of disks arecomparatively cheaper than the printed bro-chures containing the same information. In astudy it was found that the students weresatisfied with the disk except its up-to-date

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ness [15].

In another case at Rentgers University'slibrary of Science and Medicine Departmenthas also designed LSM Infomaster: a Hyper-Card based CAI program for giving introduc-tory training for all the freshly joined engi-neering students. It was found to be quiteuseful but they have not studied the impact ofthat software on the students [16].

General Electronics Corporation's Unit atEast Cleveland (GE-Lighting) has developeda prototype Machine Adjester's Helper (MAH),a PC based HT system for training theirmechanics. MAH system was designed withtwo subsystems, i.e. an HT subsystem withtextual and graphic information intended fortraining and another diagnose subsystemwhich has an expert system to diagnose thetroubleshooting production problems. Duringtheir experimental stage itself, it was found tobe very much useful in boosting both theparameters, i.e. the materials efficiency andthe machine uptime (17). It was also foundthat the system is very much user-friendlyand none of their mechanics pointed out anynegative criticism about the system.

It is generally regarded as difficult and time-consuming to design a good training pro-gramme. The teachers who design course-ware should envisage the needs of slow learn-ers as well as the intelligent students. Ingeneral, the designer of machine learningsystem unlike HT, should undertakeexpensive experimentation and debugging.Linking of fragments in the web must betested and all those sequences should beeasily available to the student to understandthe subject/topic effectively. Misunderstand-ing of the students should also be anticipatedand prevented carefully while sequencingand linking the thought contents.

REASONS FOR USING HYPERTEXT AS ATOOL FOR TEACHING/LEARNING

FOllowing are some of the reasons for usingHT as a teaching tool.

1) The main reason of using HT for teachingis that a student will use his/her optimumfreedom according to his/her choice be-cause the text in HT is presented more

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naturally than sequentially. Moreovertheboundaries of the subject fields are arbi-trarily unlike the printed book.

2) Normally while browsing a conventionalprinted book, people do not read theentire book. They generally read therequired portion from the book in theirown way. HT provides connections and.relations between the information frag-ments scattered at various places.

3) HT makes it possible for the students tomake marginal notes or highlight theportions of text.

4) Since the information in HT is arranged inassociative linked form, one can retrieveadditional depth of knowledge on aspecific aspect just by clicking on an ac-tive node with the mouse.

5) Publications are conventionally aimed at aparticular level of audience, for example,text books are for students, articles are forresearchers and so forth. In HT, a singleform could serve the purpose of theelementary reader to the adult/ad-vanced researchers; depending upon thelevel of user's interaction and the ap-proach to the database.

6) In HT, one can present the teachingmaterials, with a combination of graph-ics, animation, sound and text in a dy-namic form which is better than any otherexisting teaching aid such as CAL, Corn-puter Based Education (CBE), CBT, A-Vmaterials, etc.

7) One of the aims of HT is to improve theexisting learning practices. So in HT, themain strategy of learning is by exploringthe information by the learner, which i~ apowerful capability. Here learner is corn-pletely independent to move, learn and totake independent decisions.

8) HT also allows individual instructions tothe learner which is normally difficult in tra-ditional teaching.

9) Collaborative writing is one of the featuresof the HT which is useful for education inwhich a number of people could share the

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ideas, works, designs in their develop-ment. KMS is the best example for this.

10) lnter- linking of ideas and concepts is oneof the useful aspects of HT for teaching.Almost all the HT systems support theeasy creation and inter -linking of the in-formation f,aqrnents which will be usefulfor easy navigation and browsing the HTdatabases by the students.

11) Continuous creation and updation featureof HT is one of the many advantages forteaching which is a bit difficult and alsotime consuming process incase ofbooks and other teaching materials.

12) In HT, one can write new ideas/concepts and add individual views fortheexisting ones and also link them with theother ideas/views.

IMPACT OF HYPERTEXT ON EDUCATION

The impact of HT may be mainly envisaged inthree areas:

a) The replacement of traditional oral me-dium by the dynamic visual media withgraphics, images etc.

b) Specialized training course for the HTcourseware developer by incorporatingareas like HCI, graphics, programming,educational psychology, cognitive stud-ies, etc.

c) The development in analytical/thinking andskills of students.

Research results indicate that after using HT,students have developed their critical think-ing skills comparatively more in their teachingprocess [18]. The student who had access toHT course materials was found to grasp andunderstand better than others.

DISADVANTAGES OF HYPERTEXT

Poor designing is one of the most commonproblems in many of the HT systems. The textin the HT is in the form of broken fragments.Therefore, if the links are not successful orlogical, it will be neither attractive nor effective.So, the HT author or developer should be agood designer with a good bit of knowledge inHCI, cognition studies, computing, education

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psycholoqy. and subject knowledge.

HYPER leXT - A leACHING TOOL

Another rnsjor problem of HT is that the biggerthe system, the possibility of getting lost in thesystem is greater. In general, if the numberof nodes/chunks increase from a certainlevel, the complexity of hyperspace which isproportionate to the user's chances of get-ting-lost in the system is also increased. Eventhough different systems ace providing differ-ent methods to keep track of the users'path,the possibility of getting lost is not ruled out.Unless the user knows the reading skills andknowledge organization of HT system, hecannot make an optimum use of it. followingare some of the drawbacks of the HT system.

1) The systems are incompatible due to lackof standardization in HT systems.

2) According to theoretical definitions, so farno full fledged ideal HT system is built ..with the result that the idea is not verymuch popularized.

3) The HT database is generally very largeand a new learner finds it difficult tokeep control of it and hence losesinterest.

4) Lack of good designers of HT databases.5) In case of bigger HT ststems, they are

neither portable nor easily accessible likebooks by everybody.

6) Designer's or author's copyright for thesoftware is not well protected.

7) Learner has to put some extra effortsin remembering/concentrating on thesystem to maintain several tasks at a timewhich causes some strain on him. This iscalled 'crgnitive overhead' problem.

8) Reading of HT courseware materials ismore slower than books and also causeslot of strain on reader's eyes and mind.

CONCLUSIONS

Even though the idea of HT was introducedearlier than the development of the computer,it did not popularize just because people didnot clearly understand its main theme. Itstarted becoming popular only from the lastfour years. It was when Apple Computersstarted supplying its HyperCard system freeof cost with the purchase of any of theirMacintosh computer that the idea of HTstarted gaining popularity.

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Now HyperCard, an HM system has madeamazing impact on people's thinking and theconcept is spreading day-by-day and isbeing used for teaching in schools, collegesand universities throughout the world. Inspiteof its few drawbacks, HT has got tremendouspotential for any application in which informa-tion has to be retrieved and presentedeffectively to the users. Since the main outputof this media is in visual form which is veryfamiliar to the general public, it will definitelybecome more popular in future.Now the main task is to develop good vo-cabulary, syntax, structure and behaviour ofvarious forms of text, etc. in order to getmaximum benefits out of it. HT has profoundinfluence on education and SCholarship,especially during the past six years. It wasclearly observed that after using HT, studentsimproved skills such as creativity, flexibility,decision making, evaluation and synthesis ofinformation, confidence building etc. Design-ers of .HT system are trying their best toeliminate its drawbacks and improve theirusability. Comparatively, the number of peopleinvolved in conducting research in this fieldhas increased in multi-folds during the lastfour decades. If these systems over come theproblem of incompatibility, the mass intro-duction of hypermedia materials in educationthrough out the world is expected very soon.

REFERENCES

1. Bush V: As we may think. The AtlanticMonthly 176:1 July 1945.

2. Nelson T H: "The Hypertext" Proceed-ings of the world Documentation Fedara-tion 1965.

3. Nelson T H: Getting it out of our system.IN: Information Retrieval - a critical view.By George Schechler.Ed. Washington,D.C. Thompson Book Co, 1967. pp191-210.

4. Yankelovich N, Bernard J H, Norman Mand Steven M D: Intermedia: the con-cept and the construction of a seemlessinformation environment. IEEE Computer.1988, 21 (1),81-96.

5. Landow G P: Hypertext in literary educa-tion, criticism, and scholarship. Comput-

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ers Humanities.1988, 23 July, 173-198.

6. Beeman W 0 et a1: Intermedia - a casestudy of innovation in higher education.Providence, RI: Office of the programanalysis. IRIS: Brown University 1987.

7. Clark I L: Project Jefferson - a hypertextapplication for teaching students research

_skills. Research in word process newsl1988, 6 (9), 2-7.

8. Vandergrift K E: Hypermedia - Braking thetyranny of the text. School Lib J 1988, 35(3),30-35. .

9. Lamb A: Hypercard and video - a revolu-tionary combination for higher education.Ohio Media Spectrum 1981, 41 (Spr), 21-25.

10. Hubbard G: Hypermedia- Cause for opti-mism in art curriculum design. Art Educa-tion 1989, 42 (1), 58-64.

11. Gregory 0 C: Hypermedia - Laser video/audio technology and art education. ArtEducation 1989, 42 (1), 66-70.

12. Dyer A: The introduction of Hypertextauthoring into theoretical studies curricu-lum at Coventry Polytechnic Faculty of Artand-Design. In: Proceedings of the Hy-pertext-II. ed by Ray McAleese. UniversityTraining Centre, University of Aberdeen,1989,6.

13. Thrush 0' Frank M: An interactive hypertext of pathology. IN: Proceedings ofthe 4th annual symposium on computerapplications in medical care. IEEE, NewYork 1980, 1820-1825.

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14. Gartshore P J: The future of hypermediafor generation of flexible learning envi-ronments. 11th Information Retrieval Re-search Colloquiam. Huddersfield, 5-6 July1989.

15. Hewett T T: The Drexel Disk - Hypertext-based instructional software as a tool forthe exploration of a constrained knowl-edge space. Behaviour Research Meth-ods, Instruments & Computers 1989, 21(2),316-325.

16. Kesselman M: LSM Infomaster - a hyper-card CAI Program on a Macinthosh net-work. C&RL News 1988, July/Aug, 437-440.

17. Gall T P et al: Hypertext/expert systemfor machine diagnostics and mechanictraining. In: Proc. of Computers in Engi-neering Conference. Sanfransisco, Aug.1988. ASME: NY, 1988. 325-330.

18. Landow G P: Hypertext in literary educa-tion - Criticism and Scholarship. Comput-ers and the Humanities 1988, 23 July,173-198.

19. Florin F: Creating Interactive Video Pro-grams with Hypercard. Hyperage 1988,1(2), 1988. 38-43.

20. Mac Morrow N and Baird P: Moving intoHypermedia - Hypertext and Interactivevideo. IN: Online Information'88, Proceed-ings of the 12th International Online Infor-mation Meeting, 6-8 Dec. 1988, London,UK. Learned Information. Oxford. Vo1.1.227-237.

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