College and Research Libraries The Use of Medical Theses As Demonstrated by Journ~J Citations, 1850-1960 BY L. MILES RAISIG andFREDERICK G. KILGOUR THE STUDY reported in this paper arose from consideration of the question wheth- er the Yale medical library should retain in part or in whole its collection of some- what more than one hundred thousand .European medical theses published large- ly in the last seventy years. Experience of recent years has been that theses at- tract infinitesimal demand, which suggests that they may never have enjoyed signifi- cant amounts of use. The Yale medical library has responsibility for maintaining collections as source materials for histor- ical research, but if theses had not been used in literature of the past, there would be little if any justification in preserving such large holdings. Therefore, it was to determine whether theses had been used in older literature that this investigation was undertaken. The findings are pub- lished in the belief that they will be useful to those institutions faced with making decisions on the management of theses, both old and current, and also to those contemplating collecting theses for gen- eral or historical purposes. METHODS AND MATERIALS It was believed that an analysis of cita- tion use would provide the most signif- icant data on the medical thesis. There- fore, the following basic statistics were considered to be of primary importance and were sought and recorded: source and bibliographical data of the thesis cita- tion (journal, volume, page, year; author, title, university, year of publication); MARCH 1964 Mr. Raisig is Head, Acquisitions Section, and Mr. Kilgour is Librarian, Yale Medical Library. This investigation was pursued as part of the Selective Book Retirement Pro- gram, Yale University Library, supported by a grant from the Council on Library Resources. number of total citations, of citations to journal articles, of thesis citations, and of all other nonjournal citations. Medical journals were chosen as the best and most easily available sources of citations for analysis, their usefulness hav- ing been well established in many earlier citation studies. The period 1885-1960 was tentatively selected for analysis be- cause of the year limits of the Yale med- ical library's thesis collection, and be- cause it appeared to offer the most signif- icant data on the use of the thesis. The expected infrequency of the disser- tation citation demanded inverse sam- pling, or complete analysis, of all refer- ences appearing within the selected unit of issue of any source journal. This full analysis, together with the necessity to confine the study within the time allowed, limited the number of source journals to ten. A staggered, random pattern of source publication analysis was devised, each journal being studied in its every tenth year, so that with the exception of 1946, complete. coverage was secured from 1898 through 1961 without duplica- tion. To assure objectivity as well as sig- 93 TABLE 1. CITATION SOURCE JOURNALS JOURNAL 1821-30 Acta Physiologica Scandinavica (Skandinavisches Archiv fiir Physiologie, 1889-1940) American Journal of the Medical Sciences '29 Archivio de Fisiologia British Medical Journal Bulletin, Academie de Medecine (Paris) Bulletins et Memoires, Societe Medicale des Hopitaux de Paris Journal of Physiology Journal of the American Medical Association Miinchener medizinische Wochenschrift ( Arztliches Intelligenz-blatt, 1854-1885) . Virchows Archiv fiir pathologische Anatomie und Physiologie und Klinische Medizin nificance . in the choice of the citation population for study, nine of the ten source· journals were selected from Ash, Serial Publications Containing Medical Classics: An Index to Citations in Garri- son-Morton, 1 on showing there relatively high individual indexes of classic worth. The index for each of tlie nine journals was found by dividing the number of clas- sic articles by the number of inclusive years of publication as given in Ash's compilation. Other criteria for selecting the source journals were variety of geo- graphical origin, variety of frequency of publication, variety of articles on theo- retical, experimental, and clinical medi- cine, and number of years of publication. The tenth source journal, Archivio di Fisiologia, was chosen largely for its availability and the need for a source in Italian. The presence in the study of four journals concerned with physiology is co- incidental and unplanned. Table 1 con- tains a list of the titles and years of all journals analyzed, representing 19 5 vol- umes and part volumes. 1 Lee Ash, .Serial Publications Containing Medical Classics: An Index to Citations in Garrison-Morton (New Haven: The Antiquarium, 1961). YEARS ANALYZED 1891- 1831-40 1841-50 1851-60 1861-70 1871-80 1881-90 1900 -- ------------ '92 '39 '49 '59 '69 '79 '89 '99 '63 '73 '83 '93 '45 '55 '65 '75 '85 '95 '60 '70 '80 '90 '00 '78 '88 '98 '84 '94 '56 '66 '76 '86 '96 '51 '61 '71 '81 '91 The primary sources of citations in the investigation were original articles, as well as addresses, reports, case records and letters in the form and with the substance of original articles, correspondence re- lating to articles, and nonabstracted and unabridged proceedings. The following were exCluded ·from analysis: abstracts of articles and proceedings; editorials; book lists, reviews, and bibliographical notices; reports of societies; obituari¢s,' necrology lists, biographical notices, and appreciations; news items; legal notices; public health statistics; question and an- swer columns; dissertation lists; unsigned and noncredited materials. No attempt has been made to secure for analysis those few bibliographies omitted by the publisher for lack of space from later vol- umes of Munchener Medizinische Wo- chenschrift and Journal of the American Medical Association. The following definitions and methods have been used throughout the study. Any cited work known to have been pub- lished fewer than four times a year has been treated as a nonjournal. If the fre- quency of a cited work could not be de- 94 COLLEGE AND RESEARCH LIBRARIES TABLE 1. (Continued) JOURNAL Acta Physiologica Scandinavica (Skandinavisches Archiv fi.ir Physiologie, 1889-1940) American Journal of the Medical Sciences Archivio de Fisiologia British Medical Journal Bulletin, Academie de Medecine (Paris) Bulletins et Memoires, Societe Medicale des Hopitaux de Paris Journal of Physiology Journal of the American Medical Association Mi.inchener medizinische Wochenschrift ( Arztliches Intelligenz-blatt, 1854-1885) Virchows Archiv fi.ir pathologische Anatomie und Physiologie und Klinische Medizin *Not published 1946. termined easily without searching, the citation was included in the total count as a journal. Replicate citations occurrmg within the same source article, and refer- ring to a single work by the same author, have not been counted. This rule includes citations to theses. Each replicate citation to the same thesis, occurring in different source articles, has been recorded. Every effort has been made to identify by uni- versity and year imperfect dissertation references, of which only ten remained incomplete. 2 A citation to an unidentified author, the title of whose work has been 2 France, Ministere de I' Education N ationale. Cata- logue des Theses et Ecrits Academiques ... 1884/85- . (Paris : 1885- ) . J ahresverzeichnis der deutschen H ochschulschriften, Bd. I- , 1885. (Berlin und Leipzig: Borsenverein der deutschen Buchhlindler, 1887- ) . U. S. Armed Forces Medical Library. Index-Cata- logue of the Library of the Surgeon-General's Office, United States Army (Washington: Government Print- ing Office, 1880-95; 2d ser., 1896-1916; 3d ser., 1918- 32 ; 4th ser., 1936-55). U. S. National Library of Medicine. Index-Cata- logue of the Library of the Surgeon-General's Office, National Library of Medicine. 5th ser. (Washington: Government Printing Office, 1959-61). World Health Organization. World Directory of Medical Schools, 2d ed. (Geneva, 1957). Yale Medical Library. Card Catalog of Medical Theses. MARCH 1964 YEARS ANALYZED 1901-10 1911-20 1921-30 1931-40 1941-50 1951-60 1961-70 ---- -- -- '02 '12 '22 '32 '42 '52 '09 '19 '29 '39 '49 '59 '07 '17 '27 '37 '47 '57 '03 '13 '23 '33 '43 '53 '05 '15 '25 '35 '45 '55 '10 '20 '30 '40 '50 '60 '08 '18 '28 '38 '48 '58 '04 '14 '24 '34 '44 '54 '06 '16 '26 '36 * '56 '01 I '11 '21 '31 '41 '51 '61 omitted, has been included in the count of journal references. Dissertations accepted and recorded were: these; akademisk afhandling; proef- schrift; Inauguraldissertation; Inaugural- abhandlung; Doktorarbeit; Dissertations- arbeit; Akademische Abhandlung; and the equivalents "D.J.", "I.D.", "J.D."3 The following monographs were excluded as theses, but were included in the non- journal count: Habilitationsschrift; Fakul- tatsrede; Gratulationsschrift; concours; these de concours; these d'agrege; these d'agregation; medical nondoctoral theses; nonmedical doctoral theses. 4 Dissertations published as journal articles were counted as such; a separate recording was kept of these and of four of the classes above, and will be discussed in the results section. The citation recording technique in- volved a continuing threefold operation: the counting of every citation on a me- chanical hand counter; the tallying of every citation to a nonjournal work (ex- 3 [Medical Qualifications]. London Medical Record, X (September 15, 1882), 345-86; London Medical Record, N.S. II (September 20, 1889), 349-95. 4 Ibid. 95 Per cent 50 1821 1831 1841 1851 1861 1871 1881 1891 1901 191 1 1931 -30 -40 -50 -60 - 70 - 80 - 90 -1900 -10 - 20 - 40 Years (Decades) FIGURE 1. DISTRIBUTION OF THESIS AND OTHER NONJOURNAL CITATIONS AS PERCENTAGES OF TOTAL CITATIONS. eluding the thesis) on a special work sheet; and the separate recording of every thesis reference on a 3x5-inch slip indi- vidually numbered by source journal. Citation counts were assembled in ta- bles by journals and source years. At the completion of the analysis of each journal the percentage relationship of thesis ci- tations to all citations was plotted on a Swiss 5o/o Other So/o FIGURE 2. NATIONAL DISTRIBUTION OF THESES CITED. master line graph. This enabled ready contrast of the journal yield of citations and led to the extension of the analysis back to the middle of the nineteenth cen- tury. RESULTS A total of 2,669 citations to 2,452 in- dividual dissertations published as sepa- rate monographs turned up in the analysis of 140,534 references. Of the 2,669 cita- tions, ten are incomplete and unidentified as to place or year; except in Figure 1, these ten have been excluded from all calculations and illustrations. Figure 1 provides the distribution by decades of thesis and other nonjournal citations as percentages of total citations, and the re- lationship of nonjournal to journal cita- tions, for the period 1821-1960. There is seen here a steady growth in the citing of theses from the 0.8 per cent of 1821- 30 to the high points of 4 and 3.9 per cents in 1881-1910, with a slight fall dur- 96 COLLEGE AND RESEARCH LIBRARIES TABLE 2. DISTRIBUTION OF THESES BY UNIVERSITY Replicate Total Rank University Theses Citations Citations 1 Paris 880 83 963 2 Berlin 136 18 154 3 Miinchen 91 6 97 4 Lyons 84 5 89 5 Wiirzburg 75 6 81 6 Dorpat 68 15 83 7 Ziirich 65 3 68 8 Leipzig 59 4 63 9 Bonn . 53 2 55 10.5 Halle . 47 0 47 St. Petersburg 47 1 48 12 Mar burg 46 6 52 13 Giessen . 44 2 46 14.5 Kiel 43 1 44 Konigsberg 43 3 46 16 Breslau 41 2 43 17 Strasbourg 40 7 47 18.5 Freiburg 39 1 40 Gottingen 39 5 44 20.5 Greifswald 37 6 43 Tiibingen 37 3 40 22 Erlangen 33 4 37 23 Heidelberg 31 1 32 24 Bordeaux 28 0 28 25 Jena 26 1 27 26 Geneva 25 2 27 27 Montpellier 22 0 22 28.5 Copenhagen 21 3 24 Rostock . 21 4 25 30 Bern 16 1 17 31 Basel . 15 2 17 32.5 Lille 14 0 14 Nancy 14 0 14 34.5 Algiers 11 1 1,2 Toulouse 11 0 11 36.5 Frankfurt 9 1 10 Leyden 9 1 10 '38 Edinburgh. 8 1 9 40 Hamburg 7 0 7 Koln 7 0 7 Stockholm. 7 1 8 43 Bucharest 6 1 7 Buenos Aires . 6 0 6 Utrecht . 6 0 6 47 Amsterdam 5 1 6 Cambridge 5 1 6 ing 1871-80 stemming apparently from the effects of the Franco-German War of 1870-71. The marked decline in thesis citation which begins in the decade 1911- 20 appears not to be due wholly to World War I influences, for there is no recovery in 1921-30 and 1931-40. The continued fall from 1931 to 1960 breaks with a slight rise occurring during the period of MARCH 1964 Replicate Total Rank University Theses Citations Citations Helsinki . 5 0 5 Marseilles 5 0 5 Moscow 5 0 5 51 Glasgow 4 0 4 Lausanne 4 0 4 Uppsala .. 4 1 5 54.5 Groningen . 3 1 4 Mainz 3 0 3 Miinster 3 0 3 Pennsylvania . 3 0 3 57.5 Erfurt 2 0 2 Kazan 2 0 2 75 Athens 1 0 1 Bahia. 1 0 1 Bamberg 1 0 1 Birmingham 1 0 1 Boston 1 0 1 Brussels . 1 0 1 Budapest 1 0 1 Cape Town 1 0 1 Columbia 1 0 1 Danzig 1 0 1 Dusseldorf 1 0 1 Durh::tm 1 0 1 Florence 1 0 1 Ghent 1 0 1 Harderwijk 1 0 1 Jassy 1 0 1 Kharkov 1 0 1 Kiev 1 0 1 Lima 1 0 1 Lisbon 1 0 1 London . 1 0 1 North Carolina 1 0 1 Odessa 1 0 1 Sao Paulo . 1 0 1 Stettin 1 0 1 Turin . . 1 0 1 Victoria. 1 0 '1 Vienna 1 0 1 Warsaw. 1 0 1 Washington 1 0 1 Witwatersrand 1 0 1 Yale 1 0 1 Totals 2,452 207 2659 Total Universities: 90 the later years of World War II then reaches a low of 0.7 per cent for the last decade. The arithmetical mean of thesis cita- tions, as a proportion of total citations for the analysis years 1821-1961, is 16 per 1000. For the years· of greatest citation use, 1881-1910, the proportion is 40 per 1000. Of the 2,559 citations to identified 97 dissertations, 207, or less than 8 per cent, are replicates. The steady rise in the citation use of medical journal articles in the last hun- dred years is clearly shown in Figure 1. Citations to journal literature in the dec- ade 1941-50 accounted for 59.8 per cent of all citations found; from 1851-60 to 19 51-60 the proportion of journal cita- tions to all citations rose from 49.4 to 87.3 per cent in an apparently nonre- versible trend. This rise should not be considered the absolute cause of the per- centage loss in thesis citation use dating from 1901-10. Related measurements of use will demonstrate in the discussion fol- lowing a real decline in the citing of theses, stemming probably from a vari- ety of factors. Table 2 offers the numerical distribu- tion of theses cited and replicate thesis citations among all universities repre- sented, with a ranked list of the latter. The very great number of Paris theses is balanced by the reduced total of dis- sertations from nine other French uni- versities; the combined total of theses cited from all French universities is sixty- seven more than the total from all Ger- man universities. Berlin is the most cited of the twenty-eight German universities represented. Neither nation is favored in replicate citations to its theses; for each nation these amount to about 8 per cent of its total thesis citations. Because of its staff, tradition, and influence, Dorpat has been considered a German university outside of Germany, although it was Rus- sian politically and geographically; all Dorpat theses cited were published be- tween 1836 and 1905, almost wholly within the period of German strength. Figure 2 illustrates the national dis- tribution of individual dissertations cited. Noteworthy is the fact that French, Ger- man, and Swiss theses account for 92 per cent of the total cited, as well as the extreme paucity of British, Italian, Span- ish, and North and South American dis- sertations, greatly outnumbered in turn by Russian and Scandinavian theses. The inclusion of replicates in computing the national distribution of thesis citations favors only French theses in this propor- tion: French, 46 per cent; German, 42. per cent; Swiss, 5 per cent; others, 7 per cent. The disproportion of citations yield- ed ( 9 per cent) by the two French source journals, and of citations to French dis- sertations ( 46 per cent) is remarkable; the proportion of citations yielded by the two German source journals (32 per cent) more nearly approaches that of citations tp German theses ( 42 per cent). Illustrated in Figure 3 is the distribu- tion of the dates of publication of theses from French universities. The first notice- able rise in the number of dissertations cited occurs in the period 1851-55, and this quantity remains almost the same until 1870. In the five-year period includ- ing the Franco-German War of 1870-71 there begins a series of sharp increases in the number of citations, reaching a Citations r.35 120 105 90 7 5 6 0 45 3 0 15 0 TOTA LS Theses cit ed : 1109 Replicate c itation s : 106 Thesis C ita t ions: 1215 ~ Repli c a t e c itation s T heses ~ n ntn-· ~ (;:~~:des) ~ FF ~ I ~. I I ~ ~ ~ !]! ~ FIGURE 3. DISTRIBUTION OF FRENCH UNIVERSITY THESES BY YEARS OF PUBLICATION, 1749-1960. ~ ~~ 98 COLLEGE AND RESEARCH LIBRARIES peak in 1896-1900, falling to a low in 1916-20, and showing a fluctuating, di- minishing number from 1926 to 1960. Figure 4 portrays the distribution of the dates of publication of cited disser- tations from German universities. This is similar to the distribution of French university theses, but the first great in- crease in number occurs in 1846-50, five years earlier than the corresponding in- crease in number of French theses, and reaches its highest point in 1891-95, five years earlier than the French peak. The first marked decrease in number occurs in 1906-10, with a decline continuing to 1956-60. There are noticeably more French theses than German theses cited during the period 1921-60, and the num- ber of French theses remains more than twice that of the German number at the end of this period. In an attempt to secure an index of citation use based on the number of theses available for citation, those theses most cited-University of Paris-were chosen for sampling. During the calen- Citations 1645- 1820 Years (Decades) Ui Q) dar years 1891-1900 there we-re present- ed to the Paris medical faculty a total of 5,520 theses. 5 Within this same period it was found that forty-nine of these had been cited. By substitution in the formula number of theses subsequently cited ----------=--=--~-X 1000, number of theses originally published the index of citation use for this period was calculated to be 9. During the cal- endar years 1951-60 there was present- ed to the Paris medical faculty a total of 11,013 theses, 6 of which thirty-four were found to have been cited in the same years. By substitution in the formula above, the index of citation use for this period was found to be 3, or one-third of the index for .1891-1900. . While these indexes offered new evi- dence of the decline in the citation use of the medical thesis, they could not yield .any measurement of citation use beyond G France Ministere de l'Education Nationale. Cata- £ogue des Theses, op. cit. e Andre Hahn, Personal Communication, May 24, 1962. 26 II Estimates based on 1891-1900 index FIGURE 5. DIS.TRmUTION OF THESIS CITATIONS BY YEARS OF THESIS PUBLICATION, 1645-1960; ADJUSTED ESTIMATES OF CITATIONS TO THESES PUBLISHED 1901-1960. MARCH 1964 99 the two decades actually investigated. The Paris theses published from 1891 to 1900 were reviewed, therefore, for cita- tion use from 1891 to 1960. Of these theses 136 were cited, and this number produced for the seventy-year period an index of citation use of 25. As a further measurement of use there was computed the citation lag of Paris dissertations published 1891-1900 and cited 1891-1960. This was based on ci- tations to 13 6 individual theses and on fourteen replicate citations. It was found that 49.3 per cent of all citations occurred within the first ten years following pub- lication, and 32.7 per cent within the second ten-year period; thus, 82 per cent of the citation use life lay within the first · twenty years after publication. The re- maining 18 per cent was spread from the twenty-first to the fifty-eighth postpub- lication year. The heaviest use occurred during the first and second years follow- ing publication, in each of which 9 per cent of the citations fell. Citatiqns 135 120 105 90 75 60 45 30 15 TOTALS ·Theses cited: '1042 Replicate citations: 91 Thesis C itations: 1133 ~ Replicate citations Theses ~ ~ 8 e~~des) ~ "' ~~ ; FIGURE 4. DISTRIBUTION OF GERMAN UNIVERSITY THESES BY YEARS OF PUBLICATION, 1665-1960. There is offered in Figure 5 the dis- tribution of thesis citations by years of thesis publication, 1645-1960. There is also shown, as the concluding step in the measurement of citation use, a series of adjusted estimates of the numbers of cita- tions to theses published 1901-60. The number of citations to theses published 1891-1900, 502, was selected as a base from which the probab~ 0 use lag in the six decades to follow 19Jt> might be com--...-- puted. The same citations to theses pub- lished 1891-1900 were separated by dec- ade of citation use. For the decades 1891- 1900 through 1951-60, these citations totaled respectively 120, 204, 91, 55, 20, 6, and 6. The adjusted number of citations to theses published 1901-10 was derived from the formula citations 19 51-60 to theses published 1891-1900 total thesis citations 1891-1900 x 100 · This number, 1, was then added to the 1901-10 total of 416. The adjusted number of citations to theses published 1911-20,2, was secured with the formula citations 1941-60 to theses published 1891-1900 total thesis citations 1891-1900 x 100 , and was added then to the 1911-20 total, 178. In this way the citation total of each succeeding decade from 1901-10 through 1951-60 has been adjusted to give a figure to represent estimated cita- tions on the basis of all theses having been available for citation throughout equal periods of time. The chart clearly demonstrates the continued fall, even after adjustment, in the number of citations to dissertations published since 1900. The decline breaks in 1951-60, and there is insufficient evi- dence to determine if the 19 51-60 total represents an actual leveling-off or merely a temporary cessation in the decline. Although this study has been con- 100 COLLEGE AND RESEARCH LIBRARIES cemed primarily with the dissertation prepared for the doctorate in medicine and published and distributed as a sepa- rate monograph, other medical and non- medical theses have been found and re- corded separately: sixteen medical non- doctoral theses, including those granted by the University of Minnesota for study at the Mayo Clinic; twenty-five theses submitted for doctor of philosophy de- grees in the nonmedical sciences; twenty- nine theses de concours (competition es- says) and Habilitationsschriften (intro- duction-to-teaching essays); forty-seven medical doctoral theses published as ar- ticles in the various Scandinavian Acta and their supplements, and two similar theses published in other journals. These total 119, and with twelve replicate cita- tions account for less than 0.1 per cent of all citations analyzed. We may dismiss without further con- sideration these extra theses, with the ex- ception of those appearing as articles in journals and other serials. This type of publication in recent Scandinavian A eta is the later expression of a phenomenon associated with German medical theses since before 1895. Such publication of the latter is of particular interest, since there is reason to believe that it has been and continues to be a factor in the de- cline of the citation use of German theses in their separate monographic form. In a full count of the German univer- sity medical theses listed in J ahresver- zeichnis der deutschen H ochschulschriften every fifth year from 1895-96 through 1936,7 it was found that the number pub- lished as serial articles rose in an almost unbroken sweep from fifty-two to 547. The proportion of theses published as serial articles rose from 4.4 per cent in 1895-96 to 18.4 per cent in 1916, dropped to 3.7 per cent in 1921, then rose to 14 per cent to 1931, and de- clined to 11.7 per cent in 1936. It is re- markable to find that these two periods of increasing serial publication occurred during a continued fall in the citing of German theses as separate monographs. 7 Jahresverzeichnis, op. cit. TABLE 3 DISTRIBUTION OF GERMAN UNIVERSITY THESES PUBLISHED AS SERIAL ARTICLES IN SIX SELECTED YEARS, 1895-1921 * RANK SERIAL THESES 1 Beitrage zur klinischen Chirurgie . . . . . . . . . . 50 2 Virchows Archiv fiir pathologische Anatomie und Physiologic und klinische Medizin . . . . . . . . . . . . 32 3 Annalen der stadtischen allgemeinen Krankenhauser zu Miichen 25 4 Frankfurter Zeitschrift fiir Pathologie 18 Archiv fiir Gynakologie . . . 16 6 Deutsche Zeitschrift fiir Chirurgie . . . . 16 Monatsschrift fiir Geburtshiilfe und Gynakologie 16 8 Deutsches Archiv fiir klinische Medizin . . . 14 9 Zeitschrift fiir Hygiene und lnfektionskrankheiten . . . . 13 0 Naunyn-Schmiedeberg's Archiv fiir experimentelle Pathologic und Pharmakologie . . . . . . . . . . . . . . . . 12 10.5 Beitrage zur Klinik der Tuberkulose und spezifischen Tuberkulose-forschung 12 12.5 Pfiinger's Archiv fiir die gesamte Physiologie des Menschen und der Tiere 11 Zeitschrift fiir Immunitatsforschung und experimentelle Therapie 11 14.5 Archiv fiir Psychiatrie und Nervenkrankheiten 10 Monatsschrift fiir Psychiatrie und Neurologie 10 16.5- 104.5 114 journals, annuals, and proceedings 320 Total theses . . . . . 586 Total serials: 129 • Source: Jahresverzeichnis der deutschen Hochschulschriften, academic years 1895-96, 1900-01, 1905-06, 1910- 11, and calendar years 1916, 1921. MARCH 1964 101 Further evidence which seems to sup- port this belief is revealed when the ranks of German universities by number of theses cited (from Table 2) is compared with their ranks established from the proportions of their theses published as · serial articles (from the J ahresverzeichnis sample) . With the exception of Koln, which did not grant medical degrees until after World War I, there appears to be an inverse correlation of varying degree in their standings. Frankfurt, ranked twentieth of twenty-eight German univer- sities in distribution of theses cited, was the first of twenty-four in the proportion of its theses published in serials. Heidel- berg, seventeenth in theses cited, was second in theses published. In the same order Berlin ranked first and sixteenth. Distribution in serial article form of- fers to the dissertation of merit and sub- stance greater circulation and currency than it might secure as a separate mono- graph. This publication device, for a long period peculiar to German theses, has likely had considerable effect on the cita- tion use of the separate German mono- graphic dissertation. The following addi- tional factors have probably contributed, in varying degrees, to the universal dis- use of the separately published thesis by the medical writer: shifting emphases in medical education; the growth in the variety and number of medical journals; the stress upon currency in the communi- cation of medical information; and the team approach to medical research, with its possible minimizing of the thesis con- tribution of the individual. Table 3 offers a ranked list of serial publications containing German univer- sity dissertations in article form, derived from a complete count of theses in J ah- resverzeichnis der deutschen H ochschul- schriften, for every fifth year from 1895- 96 to 1921. 8 The wide variety of medical subjects and specialties, and the large number of serials represented, are note- worthy. - 8 Ibid. CONCLUSIONS The greatest citation use of the medi- cal thesis as a separate monograph was made from about 1880 to 1910. Theses cited in this period of heavy use have be- come a part of the historical record of medicine, and appear to have no worth now other than a clear historical value. The thesis has suffered increasing dis- use in the scientific information-commu- nication explosion of this century, and its rate of disuse is higher generally than that of books, reports, etc. Unless the trend noted since 1911-20 is broken or reversed, the thesis as a source for medical citation seems doomed to insignificance. The dissertation of today, except perhaps in the Scandinavian countries and France, appears to be little more than an educa- tional or research exercise, offering almost nothing to medical progress. Available data demonstrate only a token citation use of the thesis now. Al- though local, state and national consider- ations may demand the general collect- ing of theses as depository material, their selective collection for actual or expected historical value would appear to offer -the fairest exchange for processing ex- pended and shelf space used. The authors are grateful to Ursula E. Price, reference librarian, Yale medical library, for assistance in procuring need- ed materials; to Dr. Bruno Z. Kisch, cura- tor, Edward C. Streeter, collection of weights and measures, Yale medical li- brary, for information on German medi- cal education; to Dr. Colin White, asso- ciate professor of public health (biom- -etry), Yale University school of medi- cine, for statistical counsel; to Dr. Andre Hahn, head, library of the faculty of medicine, University of Paris, for infor- mation on Paris theses; to Lee Ash, edi- tor and research analyst, selective book retirement program, Yale University li- brary, for many useful suggestions; and particularly to the Council on Library Resources for the grant which made this study and report possible. • • 102 COLLEGE AND RESEARCH LIBRARIES