populations that scarcely need vaccina-tion, because of a low incidence of pa-ralysis, already have an abundance ofpoliomyelitis strains in the communitythat are actively immunizing childrensoon after they are born.

References and Notes

1. D. Bodian, Am. J. Hyg. 55, 414 (1952).2. D. M. Horstmann, Proc. Soc. Exptl. BRiol.

Med. 79, 417 (1952).3. , R. W. McCollum, A. D. Mascola, J.

Exptl. Med. 99, 355 (1954).4. D. Bedian and R. S. Paffenbarger, Jr., Amiz.

J. Hyg. 60, 83 (1954).5. D. Bodian, Ibid. 57, 81 (1953).6. This work was aided by a grant from the

National Foundation for Infantile Paralysis.7. J. F. Enders, T. H. Weller, F. C. Robbins,

Science 109, 84, (1949).8. J. S. Youngner, Proc. Soc. Exptl. Biol. anid

Med. 85, 202 (1954).9. J. E. Salk, J. S. Youngner, E. N. Ward,

Am. J. Hyg 60, 214 (1954).10. D. Bodian, ibid. 60, 339 (1954).11. G. Shwartzman et al., Conference on Biology

of Poliomyelitis, N.Y. Acad. Sci. 20 Jan. 1955.12. D. Bodian and H. A. Howe, J. Exptl. Med.

85, 231 (1947).13. A. B. Sabin and R. Ward, J. Exptl. Med.

73, 771 (1941).14. J. F. Kessel et al., J. Exptl. Med. 74, 601

(1941).15. H. A. Wenner and E. F. Rabe, Am. J. Med.

Sci. 222, 292 (1951).16. A. B. Sabin and R. Ward, cited in J. Mt.

Sinai Hosp. 11, 185 (1944).

17. D. M. Horstmann et al., J. Exptl. Med. 86,309 (1947).

18. D. Bodian, Am. J. Hyg. 60, 358 (1954).19. H. K. Faber and L. Dong, J. Exptl. Med.

101, 383 (1955).20. D. Bodian, Federation Proc. 13, 685 (1954).21. Pediatrics, 15, 107 (1955).22. Am. J. Hyg. 56, 78 (1952).23. W. McD. Hammon, L. L. Coriell, P. F.

Wehrle, J. Am. Med. Assoc. 151, 1272 (1953).24. Summary Report: Evaluation of 1954 Field

Trial of Poliomyelitis Vaccine. Vaccine Evalu-ation Center, Univ. of Mich., Ann Arbor,12 Apr. 1955.

25. D. Bodian, The Dynamics of Virus andRickettsial Infections, (Blakiston, New York,1954).

26. H. A. Howe, D. Bodian, I. M. Morgan, Am.J. Hyg. 51, 85, (1950).

27. H. A. Howe, Am. J. Hyg. 60, 371 (1954).

Citation Indexes for ScienceA New Dimension in Documentation

through Association of Ideas

Eugene Garfield

"The uncritical citation of disputeddata by a writer, whether it be deliberateor not, is a serious matter. Of course,knowingly propagandizing unsubstanti-ated claims is particularly abhorrent,but just as many naive students may beswayed by unfounded assertions pre-sented by a writer who is unaware of thecriticisms. Buried in scholarly journals,critical notes are increasingly likely tobe overlooked with the passage of time,while the studies to which they pertain,having been reported more widely, areapt to be rediscovered." (I)

In this paper I propose a bibliographicsystem for science literature that caneliminate the uncritical citation of frau-dulent, incomplete, or obsolete data bymaking it possible for the conscientiousscholar to be aware of criticisms ofearlier papers. It is too much to expect aresearch worker to spend an inordinateamount of time searching for the biblio-graphic descendants of antecedent pa-pers. It would not be excessive to de-mand that the thorough scholar checkall papers that have cited or criticizedsuch papers, if they could be locatedquickly. The citation index makes thischeck practicable. Even if there were noother use for a citation index than thatof minimizing the citation of poor data,the index would be well worth the effortrequired to compile it.

This paper considers the possible util-ity of a citation index that offers a new

108

approach to subject control of the litera-ture of science. By virtue of its differentconstruction, it tends to bring togethermaterial that would never be collated bythe usual subject indexing. It is best de-scribed as an association-of-ideas index,and it gives the reader as much leewayas he requires. Suggestiveness throughassociation-of-ideas is offered by conven-tional subject indexes but only within thelimits of a particular subject heading.

If one considers the book as the macrounit of thought and the periodical articlethe micro unit of thought, then the cita-tion index in some respects deals in thesubmicro or molecular unit of thought.It is here that most indexes are inade-quate, because the scientist is quite oftenconcerned with a particular idea ratherthan with a complete concept. "Thought"indexes can be extremely useful if theyare properly conceived and developed.

In the literature-searching process, in-dexes play only a small, although signifi-cant, part. Thosewho seek comprehensiveindexes to the literature of science fail topoint out that such indexes; although theymay be desirable, will provide only abetter starting point than the one pro-vided in the selective indexes at presentavailable. One of the basic difficulties isto build subject indexes that can antici-pate the infinite number of possible ap-proaches the scientist may require. Pro-ponents of classified indexes may suggestthat classification is the solution to thisproblem, but this is by no means the

case. Classified indexes are also depend-ent upon a subject analysis of individualarticles and, at best, offer us better con-sistency of indexing rather than greaterspecificity or multiplicity in the subjectapproach. Similarly, terminology is im-portant, but even an ideal standardiza-tion of terminology and nomenclaturewill not solve the problem of subjectanalysis.What seems to be needed, then, in ad-

dition to better and more comprehensiveindexes, alphabetical and classified, arenew types of bibliographic tools that canhelp to span the gap between the subjectapproach of those who create documents-that is, authors-and the subject ap-proach of the scientist who seeks infor-mation.

Since 1873 the legal profession hasbeen provided with an invaluable re-search tool known as Shepard's Citations,published by Shepard's Citations, Inc.,Colorado Springs, Colo. (2). A citationindex is published for court cases in the48 states as well as for cases in Federalcourts. Briefly, the Shepard citation sys-tem is a listing of individual Americancourt cases, each case being followed bya complete history, written in a simplecode. Under each case is given a recordof the publications that have referred tothe case, the other court decisions thathave affected the case, and any otherreferences that may be of value to thelawyer. This type of listing is particu-larly important to the lawyer, because,in law, much is based on precedent.

Citation indexes depend on a simplesystem of coding entries, one that re-quires minimum space and facilitates thegathering together of a great volume ofmaterial. However, a code is not abso-lutely necessary if one chooses to compilea systematic listing of individual cases orreports, with a complete bibliographichistory of each of them. Thus, it wouldbe possible to list all pertinent referencesunder each case with sufficient com-

Mr. Garfield is a documentation consultant withoffices at 1530 Spring Garden St., Philadelphia1, Pa.

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pleteness to give the index more of theappearance of a bibliography. However,this would result in an extremely bulkyvolume.

There are analogies in bibliographicoperations. For example, in catalogingbooks for booksellers' or library catalogs,an attempt is made to find references to

each book in one or more authoritativebibliographic sources, such as the cata-logs of the British Museum (BM), Biblio-theque Nationale (BN), or the Libraryof Congress (LC). The "authority" cardused in cataloging sometimes looks likea Shepard entry.

Another example is a book-review di-gest, in which one finds for each booktitle a series of references and selectionsfrom published reviews, critical andotherwise. Certain indexing publicationsperiorm a similar function.Some time ago I became concerned

with the problem of developing a cita-tion code for science. This was necessary

for the efficient manipulation by mechan-ical devices of entries to scientific indexes.In the course of this research I developeda very simple system for identifying an

individual scientific article that had ap-

peared in the periodical press. The re-

sulting numerical code consisted of two

parts. The first part was a serial number,used instead of an abbreviation, to iden-tify each periodical; it was similar to theserial numbers employed in the WorldList of Scientific Periodicals, by no means

a new idea. For example, Die Biblio-graphie der fremdsprachigen Zeitschrif-ten Literatur has for many years usedsuch a system to save space.

The second part of the code numberwas also a serial number, assigned to eacharticle in a particular publication, start-

ing with 1 and continuing throughout allvolumes. The code thus gives no indica-tion of year or volume number, a seriousshortcoming. The article number is alsonot unique, having been used by the Pro-ceedings of the Society for ExperimentalBiology and Medicine since its inception.These two serial numbers taken together,it can be seen, can identify any publishedperiodical article. It soon became appar-

ent, after such codes had been utilized on

an experimental basis, that the use of thecodes would facilitate the compilation ofa citation index. (Other coding systems

would be equally applicable.)A citation index to science would have

the following main characteristics. Firstthere would be a complete alphabeticlisting of all periodicals covered, in addi-tion to the code number for each periodi-cal. This list would be similar to theWorld List, but without the library hold-ings information. The main portion ofthe citation index would list in straight

numerical order the code numbers forall the articles covered. Under each codenumber, for example, 3001-6789, there

15 JULY 1955

would be listed other code numbers rep-

resenting articles that had referred to thearticle in question, together with an in-dication of whether the citing source

was an original article, review, abstract,review article, patent, or translation, andso forth. In effect, the system would pro-

vide a complete listing, for the publica-tions covered, of all the original articlesthat had referred to the article in ques-

tion. This would clearly be particularlyuseful in historical research, when one istrying to evaluate the significance of a

particular work and its impact on theliterature and thinking of the period.Such an "impact factor" may be muchmore indicative than an absolute countof the number of a scientist's publica-tions, which was used by Lehman (3)and Dennis (4). The "impact factor" issimilar to the quantitative measure ob-tained by Gross (5) in evaluating therelative importance of scientific journals,a method later criticized by Brodman(6) but used again by Fussler (7).Other advantages would also obtain.

In a way such listings would provide eachscientist with an individual clipping serv-

ice. By referring to the listings for hisarticle, an author could readily deter-mine which other scientists were makingreference to his work, thus increasingcommunication possibilities between sci-entists. It is also possible that the indi-vidual scientist thus might become aware

of implications in his studies that he was

not aware of before.Most authors like to see how their

works are received. Bringing together allbook reviews and abstracts is very im-portant, for it is not possible for an

author to keep up with the thousands ofpublications in which his contributionmight be reviewed. This applies equallyto publishers. It would not be impossibleto include books in the citation index. In-deed, as a first suggestion, the use ofLibrary of Congress card numbers as theidentifying code for books would seem

appropriate.It is necessary next to discuss some

realistic questions concerned with therealization of such an index. Bitner (8)has estimated that 30,000 cases are cov-

ered by Shepard's Citations in 1 year,

the cases and articles appearing in notmore than a few hundred publications.In 1953 about 1 million citations were

added-close to 40 citations per case.

What is the prospect in scientific litera-ture? The last published edition of theWorld List of Scientific Periodicals con-

tained more than 50,000 titles in scienceand technology. It is variously estimatedthat between 1 and 3 million new scien-tific articles are published each year. TheJournal of the American Chemical So-ciety alone publishes more than 3000 per

year, including approximately 2000 origi-nal articles. The order of magnitude is

therefore potentially from 50 to 100times as great as it is for Shepard's Cita-tions.However, not all of these 50,000 pub-

lications are being covered in our presentindexing activities, and yet this has notprevented us from continuing indexes ofstandard type or from starting new ones.Lack of complete coverage is not neces-sarily an argument against a citation in-dex. It is in fact an argument in its favor.Coverage could perhaps be limited to thelist of periodicals covered by one of theleading indexing services. This approachwould, of course, have an immediate dis-advantage. Such a subject selectionwould mean that less directly related sub-jects of interest would be excluded, andthese are the publications that the indi-vidual is least likely to cover in his ownresearch. It would be necessary to con-sider all the pros and cons in a selectiveapproach and then to determine the pos-sible utility of such a tool. For example,would a citation index to the 1500 peri-odicals covered by the Current List ofMedical Literature be of real value, or,similarly, a citation index to the 5000periodicals covered by Chemical Ab-stracts? The Current List would, in fact,offer a good starting point, since it al-ready provides a unique code for the100,000 items indexed by it each year.Presumably these are the most significantcontributions in the covered fields for theyear. If 10 is the number of references inthe average article, then about 1 millioncitations would be involved. The prepa-ration of that number annually is not un-

reasonable. Shepard's has already usedwell over 50 million citations in its pub-lishing activities.The ultimate success of a citation in-

dex would depend on many factors. Forexample, if each periodical would assignunique code numbers to the articles pub-lished, it would be possible for authorsto list these numbers in their bibliogra-phies and, thus, to save the work of cod-ing on the part of the citation index staff.It is unlikely that such a developmentcould take place in less than 5 or 10years, but it is comparable to the problemof getting publishers to include Libraryof Congress card numbers in their pub-lications.When such a large volume of data is

to be handled, mechanical devices ofhigh speed and versatility could be usedto great advantage and would probablydetermine success or failure. Once thecoding is done, compilation itself is quitemechanical. This could be done by means

of conventional filing slips; the Shepardorganization itself has used them success-fully for 80 years. However, it would befacilitated by a mechanical approachusing punched cards.The utility of a citation index in any

field must also be considered from the

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point of view of the transmission ofideas. A thorough scientist cannot besatisfied merely with searching the litera-ture through indexes and bibliographiesif he is going to establish the history ofan idea. He must obviously do a greatdeal of organized, as well as eclectic,reading. The latter is necessary becauseit is impossible for any one person (theindexer) to anticipate all the thoughtprocesses of a user. Conventional subjectindexes are thereby limited in their at-tempt to provide an ideal key to the lit-erature. The same may be said of classi-fication schemes. In tracking down theorigins of an idea, the citation index canbe of real help. This is well illustrated byan example from my own experience.Many years ago the Radio Corporation

of America developed a reading-aid forthe blind (9). This device had an elec-tronic system for converting printed let-ters into recognizable sound patterns.Using the device, a blind man could scana printed page; in a set of headphoneshe could hear a series of sound patterns,each letter having its own recognizablesound pattern. In effect, the words werespelled out, letter by letter, in code. Iwas particularly interested in this devicebecause I had been independently work-ing on a device that would copy print,letter by letter, and reproduce it forbibliographic and other purposes. Thetwo devices had something in common inthat they both employed scanning de-vices. I then wanted to learn whetheranyone had ever suggested that the RCAreading-aid could be used for this pur-pose. It will be apparent that if anyonehad known of the RCA device and hadthought of adapting it for copying pur-poses, a reference to the article mighthave been made. This reference couldeasily have been included in an articleor patent that was not at all related tothe problem of reading devices. A cita-tion index would have given me justwhat I was after. Nothing could substi-tute for extensive reading, but a greatdeal of time could have been saved bvbringing the appropriate works to my at-tention.

In the course of my reading I did finda few references to this device, one in abook (10), and several others in peri-odical articles, one of which was a Ger-man article on the mechanization ofphilological analyses and concordancebuilding. The latter article (11) did notdiscuss my own special interest in copy-ing devices, but it did show the similaritybetween the author's and my own think-ing from the point of view of letter-rec-ognition devices, which is what the RCAdevice attempts to be. In other words,both of us were interested in this deviceas a letter-recognition device for theanalysis of text.

110

In another instance the RCA articlewas unexpectedly cited in the joumalElectronic Engineering in an article oninformation theory (12) that I was read-ing because of an entirely different in-terest. No subject indexer could have an-ticipated this crossbreeding of interests.Perhaps there are many other articlesand books unknown to me that havemade similar references to this device.How can they be located when the mainsubject matter of the article is, on thesurface, so unrelated in nature?One might say that it would be pos-

sible to index articles more thoroughlyto achieve the same results. For example,the article on information theory, if thor-oughly indexed, might have included anentry under reading devices for the blind.Yet if this were done, our periodical in-dexing services would clearly becomehopelessly overloaded with material thatis not necessary to lead us to the microunit-the entire article or one of itsmajor sections. Although it might be saidthat no scientist interested in the greatercomprehensiveness to be found in a cita-tion index would object to having such agreat mass of references in a subject in-dex, this is impracticable. It would re-quire an army of indexers to read thearticles and identify the exact subjectmatter of every paragraph or sentence.Yet this would be necessary. To illustrate,it is only in the very last paragraph ofthe article on information theory that onewould find a reference to reading devicesfor the blind.Were an army of indexers available, it

is still doubtful that the proper subjectindexing could be made. Over the yearschanges in terminology take place, thatvitiate the usefulness of a standard sub-ject index. To a certain extent, this isovercome through the citation approach,for the author who has made referenceto a paper 40 or 50 years old has inter-preted the terminology for us. By usingauthors' references in compiling the cita-tion index, we are in reality utilizing anarmy of indexers, for every time anauthor makes a reference he is in effectindexing that work from his point ofview. This is especially true of reviewarticles where each statement, with thefollowing reference, resembles an indexentry, superimposed upon which is thefunction of critical appraisal and inter-pretation. To the indexer this has its ad-vantages as well as its disadvantages(13).To determine in a practical way what

the citation index could offer, it was de-cided to track down the citations madein one journal to a single significant ar-ticle, in order to compile a sample entryfor the citation index. At the suggestionof Erich Meyerhoff, I selected HansSelye's famous article on the general

adaptation syndrome (14). A systematic.search was then made of all papers thatwere published in the Journal of ClinicalErdocrinology subsequent to Selye'spaper up to 1951-a period of 5 years,including well over 500 articles. Everybibliography in each of the 500 articleswas checked for a reference to Selye'sarticle. Twenty-three articles were foundto make such reference; each of themwas then checked for the character ofthe information provided.

Examination of the citation list (Table1 ) shows the great variety of subject mat-ter included. One thing became quiteclear, even to the uninitiated-that is, theinfluence of Selye's article has been quitepronounced. Such evidence is extremelyvaluable to the historian.

It is interesting to note that, althoughall the articles cited were indexed inQuarterly Cumulative Index Medicus,not one is to be found there under theheading "Adaptation." In fact, it is sur-prising not to find any articles from thisjournal under this subject heading.

It also becomes quite obvious thatmany references to Selye's paper weregeneral and contribute little or nothing

Table 1. Index sample based on articleby Hans Selye, "General adaptation syn-drome" [J. Clin. Endocrinol. 6, 117(1946) ]. The code number for this journalin the World List is 11,123a; the articlenumber is arbitrarily taken as 687; andthe code number for the article is 11123a-687. The 23 articles that cited Selye'sarticle are listed, followed by A hypo-thetical citation index entry for Selye's-ttticle. R, review article; A,.-abstract; 0,original article.

1. Williams, R. H.: Thyroid & AdrenalInterrelations, 7: 52-57 (1947).

2. Venning, E. H.: Glycogenic Corti-coids, 7: 79-101 (1947).

3. Forbes, et al.: 17-Ketosteroids inTrauma and Disease, 7: 264-288(1947).

4. Talbot, et al.: Excretion of 11-Oxy-corticosteroids, 7: 331-350 (1947).

5. Castillo, E. B. del, et al.: Syndromeof Rudimentary Ovaries, 7: 385-422(1947).

6. Forsham, P. H., et al.: PituitaryAdrenocorticotropin, 8: 15-66(1948).

7. Pincus, G., et al.: Rhythm in BipedExcretion, 8: 221-226 (1948).

8. LeCompte, P. M.: Width of AdrenalCortex in Lymphatic Leukemia, 9:158-162 (1949).

9. Wolfson, W. Q.: 17-Ketosteroids inGout, 9: 497-513 (1949).

10. Stein, H. J., et al.: Hormonal Re-sponse to Heat and Cold, 9: 529-547(1949).

11. Davis, M. E.: Eosinophils in Preg-nancy and Labor, 9: 714-724(1949).

12. Conn, J. W.: Na and Cl of Sweat asCortical Index, 10: 12-23 (1950).

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13. Recant, L., et al.: Effect of Epine-phrine on Eosinophils, 10: 187-229(1950).

14. McArthur, J. W.. et al.: UrinaryExcretion of Corticosteroids in Dia-betic Acidosis, 10: 307-312 (1950).

15. Bors, E.: Fertility in ParaplegicMales, 10: 381-398 (1950).

16. Grossman, S., et al.: Idiopathic Lac-tation following thoracoplasty, 10:729-734 (1950).

17. Cooper. J. S., et al.: Metabolic Con-sequences of Spinal Cord Injury, 10:858-870 (1950).

18. Hioco. D.: Adrenal Metabolites inBronchial Asthma, 10: 1570-1578(1950).

19. Jailer, J. W.: Pituitary-Adrenal Sys-tem in Infants, 11: 186-192 (1951).

20. Deane, H. W.: The Adrenals in Ex-perimental Hypertension, 11: 193-208 (1951).

21. Hioco, D., et al.: Epinephrine andACTH in Bronchial Asthma, 11:395-407 (1951).

22. Schaffenberg, C. A., et al.: p-Hy-droxypropiophenone (PHP) andother so-called pituitary inhibitors,11: 1215-1223 (1951).

23. Talbot, N. B., et al.: Urinary Water-Soluble Corticosteroids, 11: 1223-1236 (1951).

Citation Index Entry11123s-687

464-9789(R)869-3366 (R)1105-9876(A)1123-4432(R)

al l,123-0752(0)-0779(0)-7264(0)-7331(0)-7385 (0)-0866(0)-8221(0)-9158(0)-9497 (0)-9529(0)

to the readers' enlightenment, since exactpage references are not provided. In sev-eral cases the Selye article is even citedbut not referred to in the text. Selye's in-fluence on all of these authors is quiteapparent. In particular instances the ci-tations are of value in locating confirma-tory evidence of some of Selye's claims.

Thus, in the case of a highly significantarticle, the citation index has a quanti-tative value, for it may help the historianto measure the influence of the article-that is, its "impact factor." With regardto a less significant work, one would sus-pect that the bibliographic advantagesmight be increased, because the scientistor librarian would be provided with ref-erences not to be found in conventionalindexes. The preliminary evidence pre-

sented indicates that the citation indexoffers interesting possibilities for anotherapproach to bibliographic control.The -next step in compiling the index

for the Selye article would be to seek outadditional references to it in more periph-eral journals, but obviously the fartheraway you get from the immediate subjectarea of the main article, the fewer thereferences to it you will locate. Yet thesemay well be the most useful references ofall, for the cross-fertilization of subjectfields is one of our most important prob-lems in science literature.

It will be well to close with a briefdescription of how the citation indexmight be compiled. The first step wouldbe the selection of the particular groupof periodicals to be covered; next, theperiod to be covered, say, only that since1900.The problem actually has two facets:

the selection of periodicals to be coveredin order to obtain citations, and the selec-tion of those articles for which we wanta citation record. For example, all ar-ticles in journals in the Current List ofMedical Literature that have remainedin continuous publication since 1900might be coded, in which case the Jour-nal of Clinical Endocrinology would notbe included. However, we might includeas citation sources all journals coveredby the Current List. Thus, the bibliogra-phies appearing in articles in the Journalof Clinical Endocrinology would supplyreferences to the basic group of articles.Each coder would be assigned a group

of articles in a particular journal. Thefirst step would be to number each articlein the journal in ascending order, byutilizing a complete table of contents ofthat journal from its inception.Once a code number has been assigned

to each article, the proper codes maythen be assigned to each periodical. Thismight be the number given in the WorldList, with new numbers for any periodi-cals not to be found there.

Actual coding starts with the first ar-ticle in a particular periodical. The coderprepares a 3- by 5-in. card for each cita-tion made in the article. Each cardshould give (i) the code number for theciting article, (ii) the code number forthe article cited, and (iii) a classificationof the citing article as an original con-tribution, review article, abstract, and soforth.Many references will be excluded by

the limits of coverage set up. Thus allreferences to articles not in the prescribedlist of journals would be excluded.

All books would be excluded unlessotherwise specified, in which case thereference card would carry the code for

the citing article and the code for thebook (its LC card number).

After all the articles had been coded,it would next be necessary to sort thecards by the code numbers for the itemscited. This would yield a group of cardsfor each cited article. These would thenbe sorted by code numbers for the citingarticles. This completes the coding andsorting. The next step would be prepara-tion for the printer.From this description it will be appar-

ent that, although a great volume of ma-terial is to be covered, relatively unskilledpersons can perform the necessary codingand filing. Professional supervision wouldstill be required, because certain decisionsrequire skilled judgment, for example,when ibid. or loc. cit. must be carefullyinterpreted. Footnotes tend to ma-ke cod-ing somewhat cumbersome. The code Ihave described is merely an example usedto illustrate the method in principle. Ifthe system were adopted, then in thefuture every author ought to be requiredto include the serial number of each itemhe referred to, so as to facilitate not onlythe compilation of citation indexes butalso other operations such as requests forreprints (15, 16).

In a certain sense a citation index isnot very different from a compendiumlike Beilstein, which gives a rather com-plete record of a compound, compiledby a similar method. A citation indexfor the literature of chemistry would un-

doubtedly make the preparation of suchworks as Beilstein much easier than it isat present. The new bibliographic tool,like others that already exist, is just astarting point in literature research. Itwill help in many ways, but one shouldnot expect it to solve all our problems.

References and Notes

1. P. Thomasson and J. C. Stanley, Science 121,610 (1955). Thomasson and Stanley were com-

menting on C. Zirkle's discussion of the use

of fraudulent data [Science 120, 189 (1954)].2. W. C. Adair, Am. Documentation 6, 31

(1955).3. H. C. Lehman, Sci. Monthly 78, 321 (1954).4. W. Dennis, ibid. 79, 180 (1954).5. P. L. K. Gross and E. M. Gross, Science 66,

385 (1927).6. E. Brodman, Med. Library Assoc. Bull. 32,

479 (1944).7. H. H. Fussler, Library Quart. 19, 19 (1949).8. H. Bitner, personal communication, April

1954.9. V. K. Zworykin and L. E. Flory, Proc. Am.

Phil. Soc. 91, 139 (1947).10. R. R. Shaw, Machines and the Bibliographi-

cal Problems of the Twentieth Century (Univ.of Illinois Press, Urbana, 1951) p. 19. (Re-printed from Bibliography in an Age of Science(Univ. of Illinois Press, Urbana, 1951).

11. R. Busa, Nachr. Dokumentation 3, 14 (1952).12. A. M. Andrew, Electronic Eng. 25, 471 (1953).13. E. Garfield, "Review literature as a source of

critical entries for scientific indexes, unpub-lished paper, December 1952.

14. H. Selye, J. Clin. Endocrinol. 6, 117 (1946).15. E. Garfield, Science 120, 1039 (1954).16. J. A. Behnke, Science 120, 1055 (1954).

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