A comparison of biomedicaldatabasesBy Alexander Y. Mychko-Megrin, M.D.*Scientific Worker

Department of Anesthesiology and Reanimation in DentistryN.A. Semashko Moscow Medical Stomatological InstituteDelegatskaya Street 20/1Moscow 103473, U.S.S.R.

Various published bibliographic and abstract services covering theperiod 1970-1988 were compared to analyze scope and coverage.A total of 7,281 articles and book titles (1,655 Soviet and 5,626foreign) were selected on forty-one topics in different medical fields.The titles originated from three different samples but included allSoviet medical literature on the subjects. A distribution of biomedicalserials from five databases is given by country, and twelve indices toassess the quality of biomedical databases are suggested.

INTRODUCTION

The scope and coverage of the Soviet and foreigntliterature in the major bibliographic and abstractingservices of seven countries was studied to determinethe percentage of unique references in each source.All available literature [1-2] was scrutinized and thedegree of overlap between the sources and the geo-graphic distribution of serial titles was studied, usingmanual searching techniques.An initial review of books and journals on the sub-

ject "surgical complications of helminthiasis," overthe period 1957-1969, was undertaken in 1970. Thebibliographic and abstract services of five countriesyielded 407 citations. Index Medicus®t (IM) and theCurrent List of Medical Literature indexed 50% of them,including 21% of the Soviet literature and 60% of theremaining world literature. An analysis of the foreignliterature is given in Table 1. The Soviet literaturewas covered better by the catalogs of the State CentralScientific Medical Library (SCSML) (83%) and the bib-liographic index Nauchnaya Meditsinskaya LiteraturaSSSR (Scientific medical literature of the U.S.S.R.) (65%)[3].An analysis of the forensic medicine literature cov-

erage in BIOSIS Previews® §, CA (Chemical Abstracts)SEARCH, EMCS (Excerpta Medica Computer System),

MEDLINE® * *, and SCISEARCH®tt on ten topics in-dicated that on two topics CA SEARCH included 33%and 40% of all references retrieved. For all topicsBIOSIS Previews included 23% (5% unique); SCI-SEARCH, 26% (7% unique); EMCS, 56% (26% unique);and MEDLINE, 57% (26% unique) [4].

The Soviet literature was covered better by thecatalogs of the State Central Scientific Medical Li-brary (SCSML) (83%) and the bibliographic indexNauchnaya Meditsinskaya Literatura SSSR (Sci-entific medical literature of the U.S.S.R.) (65%).

On the subject "chemical toxicology," a number ofsources, including index and abstracting services andpersonal files, yielded 223 citations as a result of sixqueries which were performed both manually andonline (Table 2). Personal files contained 22.9% of theunique references; TOXLINE®, 8.5%; CANCER-LINE®t, 4.3%; Chemical Abstracts, 3.3%; MEDLINEand EMCS, 1.9%; SCISEARCH, 1.1%; and BIOSIS, 0%[5].Mori studied the coverage of the 1985 literature on

the drug interactions of cimetidine using RINGDOC,BIOSIS, MEDLINE, and EMCS [6]. In the four data-

* Address communications to the author to Vinnitskaya street 5,flat 213, Moscow B-192, U.S.S.R. 117192.t In this article "foreign" is defined as non-Soviet.t Index Medicus is a registered trademark of the National Libraryof Medicine.§ BIOSIS Previews is a registered trademark of BIOSIS.

* * MEDLINE is a registered trademark of the National Library ofMedicine.tt SCISEARCH is a registered trademark of the Institute for Sci-entific Information.14 TOXLINE and CANCERLINE are registered trademarks of theNational Library of Medicine.

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Comparison of databases

Table 1Coverage of foreign* articles on helminthological diseases (n = 299)

Source title coverage

Index Medicus (IM) and Current List of Medical Literature 60%Helminthological Abstracts 29%Tropical Diseases Bulletin 25%Meditsinskij Referativnyi Zhumal(MRZ) Sections III and IV 14%State Central Scientific Medical Ubrary (SCSML) MoscowCatalog of foreign periodical aricles 16%

bases, 100 references were retrieved: MEDLINE 22%,EMCS 35%, BIOSIS 44%, and RINGDOC 49%. Ap-proximately 20% of the references retrieved fromBIOSIS were not yet recorded in RINGDOC.

In a comparison of sources for the literature onsuicide prevention, 103 citations were found in EM-BASE, Health Care and Administration, MEDLINE, Hos-pital Literature Index HLTH, PsycINFO® §§, and MEDB(BRS full-text medical books). MEDB yielded fourbooks (3.9%), and 99 citations were found in the otherdatabases. Sixty-three (61.2%) articles were unique, 5from HLTH, 9 from EMBASE, 24 from MEDLINE, and25 from PsycINFO. Thirty-six (35%) citations over-lapped two or more databases. A search of MEDLINEyielded 59 (57.3%) of the titles; PsycINFO, 43 (41.7%);EMCS, 32 (31.1%); and HLTH, 23 (22.3%) [7].

In 1986, the literature retrieved from a comparativestudy of two topics in twelve bibliographic and six-teen abstract databases was studied. A search on "cu-taneous changes and pathology of muscles, bones, andjoints in dermatomyositis, scleroderma, and system-atic lupus erythematosus" for the period 1977-1985yielded 751 citations. The search was made in threesections of Excerpta Medica (EM), Bulletin Signaletique(BS), Meditsinskij Referativnyi Zhurnal (MRZ), GermanMedical Abstracting Journals (GMAJ), IM, and the Na-tional Library of Medicine (NLM) Current Catalog (Ta-ble 3) [8].

In 1987 twelve bibliographic and abstracting ser-vices of six countries were compared using manualsearching. Catalogs of the SCSML included 1,277(80.5%) of 1,586 Soviet references found, the recur-ring bibliography of the Reference BibliographicMedical Bureau of the SCSML covered 56.0% of Soviettitles, Referativnyi Zhurnal (RZh) VINITI contained78 (15.2%) of 514 Soviet references, MRZ retrieved 44of 1,278 citations; a total of 93.0% of the citations werefound in the Soviet sources. The remaining 7.0% ofthe Soviet literature was cited only in foreign ser-vices. IM covered 15.1% of the Soviet literature, EM4.9%, BS 2.1%, and GMAJ 2.0% [9].

Table 2Coverage of "chemical toxicology" literature (n = 223)

Souce til % coverage

Personal files 78.3%TOXLINE 54.7%Chemical Abstracts 35.9%MEDLINE 30.6%CANCERLINE 26.6%RINGDOC 18.7%BIOSIS 16.3%Excerpta Medica 15.2%SCISEARCH 8.5%

The scope of the coverage of available literature inindexing and abstracting services decreases with anincrease in the number of sources searched. Exami-nation of the indexing and abstracting services of fourcountries on nineteen subjects revealed that IM listed1,074 of a total of 1,961 articles (54.8%) and EM 627(32.0%). BS covered 241 (27.4%) of 880 articles, RZhVINITI yielded 263 (26.6%) of 991 titles, GMAJ in-dexed 97 (16.9%) of 574 titles, and MRZ, 181 (10.9%)of 1,668 items. Increasing the number of countrysources and reducing the number of subjects to six-teen resulted in a smaller percentage coverage: IM,1,328 (48.6%) of 2,734 articles; EM, 774 (26.8%) of 2,887;BS, 637 (26.7%) of 2,385; RZh VINITI, 82 (22.5%) of365; MRZ, 389 (14.0%) of 2,786; and GMAJ, 361 (13.0%)of 2,790 articles [10].

METHODOLOGY

Detailed data comparing the scope and coverage ofvarious bibliographic and abstracting services by theauthor was published in 1987. Thirty-nine subjects inthe time period 1970-1987 were searched manually[11]. In 1988, the author studied two additional sub-jects for coverage overlap. The subject "electroen-cephalography in epilepsy in children and the ge-netics of epilepsy" yielded 369 foreign citations forthe period 1983-1987. The search for citations on"Hirschsprung's disease in children" for the period

Table 3Results of "cutaneous changes" searches (n = 751)

% yield ofrite citations

Bulletin Signaletique (BS) 51.7%Index Medicus (IM) and NLM Current Catalog 45.3%Excerpta Medica (EM) 29.8%MRZ 23.4%GMAJ 15.8%Resufts from combination searches yilded IM and EM 62.4%IM and BS 75.9%IM, EM, and BS 83.9%

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304 Bull Med Libr Assoc 79(3J July 1991

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1980-1988 retrieved 62 Soviet citations and 409 for-eign ones. Biomedical serials were defined as medicaland allied sciences journals by four international bib-liographic and abstracting services.

RESULTS

For this study, a total of 7,281 articles and book titleson 41 medical subjects were identified-1,655 Sovietand 5,526 foreign. The catalogs of the SCSML yielded1,356 (81.8%) of the Soviet items. The recurring bib-liography of the Reference Bibliographic Medical Bu-reau of the SCSML covered 219 (56.0%) of 391 Soviettitles, and MRZ listed 45 (2.8%) of 1,636 Soviet items.A total of 6.7% of Soviet titles were located only inforeign services, probably due to quicker indexingand a greater number of assigned subject headings.

Table 4 indicates the scope of coverage of availableforeign medical literature on 18 subjects in 17 servicesfrom 7 countries. Also shown are the number ofunique references and the overlap of citationsfound in the major online databases Science CitationIndex® * * * (SCI), IM, EM, and BS, together with thenumber of titles found in other services. The greatestcoverage of available literature was found in spe-cialized databases: Ophthalmic Literature 61.2%, and theIndex to Dental Literature (IDL) 55.9%. The greatestnumber of unique citations was found in IM (46.0%)and the Minerva Medicobibliografica (44.2%). The latterceased publication after 1975. The percentage ofunique references found was 39.8% in RZh VINITI,39.4% in IDL, 37.8% in MRZ, and 33.8% in DentalAbstracts. The average percentage of overlap from onedatabase compared to the other services was 64.4% inCurrent Contentsttt Clinical Medicine (CCCM),55.0% in SCI, 46.5% in IM, 30.3% in EM, 28.8% inCurrent Contents Life Sciences (CCLS), 25.9% in BS,and 23.7% in Biological Abstracts (BA).EM and BA provide a geographic listing of serials,

but also include agricultural, biological, and othertitles that are not of primary interest to physicians.Table 5 gives the geographic distribution of biomed-ical serials in five major services in 1987. Also shownare subtotals for different groupings of countries [12].

Pascal Explore provided the greatest coverage forLatin American countries (3.0%) and African coun-tries (1.4%). EM provided the greatest coverage forArab countries (1.8%). The percentage of indexed ti-tles from western countries varied from 65.3% in MRZto 85.0% in PASCAL, and the percentage of indexedbiomedical serials from twenty developed countriesvaried from 90.4% in EM to 94.8% in GMAJ. EM cov-

ered the largest number (225 or 6.6%) of Japaneseserials (Table 5).

DISCUSSION

Little data exist on the scope and coverage of muchof the available medical literature. Manual searchingof the major bibliographic and abstracting services islaborious and time-consuming, and online searchingcannot be performed on all sources. Studies show,however, that online searching is 5-10% more effec-tive than manual searching [13]. The summary datafrom this study on 41 topics in different medical fieldscovering 1,655 Soviet articles and 5,626 foreign onesprovides an opportunity to derive an average per-centage of the coverage of the available Soviet andforeign medical literature in the bibliographic andabstracting services.There is considerable overlap between different da-

tabases (Table 6). The overlap between two databases,for example IM and EM, can be evaluated in two ways:overlap in IM titles recovered in EM (43.0%) and over-lap in EM titles retrieved in IM (27.2%). Table 4shows the overlap of articles and book titles fromindexing and abstracting services with references ob-tained from the major online databases (SCI, IM, EM,and BS). These data are significant for developingsearch strategies in different online databases.Overlap of titles retrieved in BS with those found

in other bibliographic and abstract services variedfrom 24.5% with BA to 58.3% with CCCM. IM overlapwith other services varied from 13.4% with BA to57.9% with CCCM. Overlap of EM with other servicesvaried from 24.0% with BA to 61.8% with CCCM. SCIoverlap varied from 25.4% with BA to 80.2% withCCCM.Given the development of online search capabili-

ties in which several databases can be reviewed si-multaneously, there is an objective necessity to di-minish overlap and increase coverage throughcooperative agreements on serials covered. Of the1,580 dental serials covered in 1986 in the major den-tal and bibliographic services, only 452 (28.6%) of theworld literature was indexed [14].

Specialized bibliographic and abstract services areusually characterized by a low percentage of uniquereferences and a high percentage of overlap with oth-er databases. For example, of 71 titles in OphthalmicLiterature, 50.7% overlapped EM, 49.3% overlappedIM, and 18.3% overlapped the French database BS.Overlap between databases can also be evaluated

on the basis of journal title overlap. The total numberof unique titles from EMBASE (1988) and MEDLINE(1987) is 6,030. Of these EMBASE contains 4,349(72.0%)-2,143 unique (35.5%), and MEDLINE 3,881(64.3%)-1,689 unique (28%). There is an overlap of2,206 titles (36.5%) [15].

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Table 5Geographic sources for indexed articles from five sources in 1987

Excerpta IndexMedica Medicus Pascal MRZ GMAJ

Country Number (%) Number (%) Number (%) Number (%) Number (%)

Argentina 10 (0.29%) 7 (0.25%) 5 (0.19%) 6 (0.26%) 3 (0.24%)Australia 39 (1.14%) 21 (0.75%) 13 (0.51%) 16 (0.71%) 10 (0.81%)Austria 20 (0.58%) 15 (0.54%) 16 (0.62%) 20 (0.88%) 10 (0.81%)Bangladesh 6 (0.17%) 2 (0.07%) - - - - - -Belgium 38 (1.1 1%) 30 (1.08%) 20 (0.78%) 30 (1.32%) 22 (1.78%)Brazil 28 (0.82%) 15 (0.54%) 34 (1.33%) 10 (0.44%) 1 (0.08%)Bulgaria 27 (0.79%) 9 (0.32%) 2 (0.08%) 26 (1.15%) 3 (0.24%)Cameroon 1 (0.03%)Canada 35 (1.02%) 31 (1.11%) 23 (0.90%) 19 (0.84%) 9 (0.73%)Chile 6 (0.17%) 5 (0.18%) 3 (0.12%)China 16 (0.47%) 31 (1.1 1 %) 3 (0.12%) 6 (0.26%) 3 (0.24%)Colombia 3 (0.09%) - - 4 (0.16%)Comoro Islands - - - - 1 (0.04%)Costa Rica 3 (0.09%) 1 (0.04%) 2 (0.08%) 1 (0.04%)Cuba 4 (0.12%) 1 (0.04%) 5 (0.19%) 14 (0.62%)Czechoslovakia 51 (1.49%) 40 (1.44%) 8 (0.31%) 52 (2.29%) 18 (1.45%)Denmark 39 (1.14%) 47 (1.69%) 39 (1.52%) 29 (1.28%) 27 (2.18%)Dominican Republic 1 (0.03%) -

Ecuador - - - - 2 (0.08%)Egypt 2 (0.06%) 1 (0.04%) 3 (0.12%) - - 1 (0.08%)El Salvador - - - - 1 (0.04%)Ethiopia 1 (0.03%) 1 (0.04%) 1 (0.04%) -

Finland 10 (0.29%) 9 (0.32%) 1 (0.04%) 6 (0.26%) 5 (0.40%)France 163 (4.75%) 89 (3.20%) 306 (11.92%) 144 (6.35%) 79 (6.38%)French Polynesia - - - - 1 (0.04%)Germany, East 53 (1.55%) 51 (1.83%) 23 (0.90%) 54 (2.38%) 53 (4.28%)Germany, West 306 (8.92%) 227 (8.16%) 225 (8.77%) 227 (10.01%) 259 (20.90%)Great Britain 430 (12.54%) 362 (13.01%) 393 (15.30%) 204 (8.99%) 143(11.54%)Greece 6 (0.17%) 1 (0.04%)Hong Kong 2 (0.06%)Hungary 24 (0.70%) 18 (0.65%) 1 (0.04%) 34 (1.50%) 11 (0.89%)India 53 (1.55%) 25 (0.90%) 24 (0.94%) 26 (1.15%) 4 (0.32%)Indonesia - - 1 (0.04%) 1 (0.04%) -

Iran - - - - 2 (0.08%) - - - -Iraq 1 (0.03%) - - 2 (0.08%)Ireland 4 (0.12%) 2 (0.07%) - _ - _ 1 (0.08%)Israel 6 (0.17%) 5 (0.18%) 2 (0.08%) - - 1 (0.08%)Italy 181 (5.28%) 85 (3.06%) 20 (0.78%) 108 (4.76%) 48 (3.87%)Ivory Coast - - - - 4 (0.16%)Jamaica 1 (0.03%) 1 (0.04%) 1 (0.04%)Japan 225 (6.56%) 130 (4.67%) 59 (2.30%) 119 (5.25%) 47 (3.79%)Jordan 1 (0.03%) - - - - 1 (0.04%) -

Kenya 1 (0.03%) 1 (0.04%) 2 (0.08%)Korea, South 11 (0.32%) 1 (0.04%) 1 (0.04%)Kuwait 2 (0.06%) - - - - - - - -Lebanon - - 2 (0.07%) 1 (0.04%) -

Luxembourg 1 (0.03%) 1 (0.04%) - - 1 (0.04%) 1 (0.08%)Madagascar 1 (0.03%) 1 (0.04%) 1 (0.04%) 1 (0.04%)Malaysia 2 (0.06%) 1 (0.04%) 1 (0.04%)Martinique - - - - 2 (0.08%) -Mexico 16 (0.47%) 11 (0.40%) 12 (0.47%) 3 (0.13%) 2 (0.16%)Mongolia - - - - - - 1 (0.04%)Morocco 2 (0.06%) 1 (0.04%) 3 (0.12%)Mozambique - - - - 1 (0.04%)Nepal - - - - 1 (0.04%) - - - -Netherlands 156 (4.55%) 101 (3.63%) 141 (5.49%) 74 (3.26%) 43 (3.47%)New Zealand 5 (0.15%) 5 (0.18%) 1 (0.04%) 3 (0.13%) 2 (0.16%)Nigeria 1 (0.03%) - - 1 (0.04%)Norway 10 (0.29%) 11 (0.40%) 6 (0.23%) 6 (0.26%) 7 (0.56%)Pakistan 2 (0.06%) 1 (0.04%) - - 1 (0.04%) -

Panama - - 1 (0.04%)Papua New Guinea - - 1 (0.04%) 1 (0.04%)Peru 1 (0.03%) - - 2 (0.08%)Philippines 3 (0.09%) - - 2 (0.08%) -

Poland 44 (1.28%) 48 (1.73%) 4 (0.16%) 60 (2.65%) 12 (0.97%)Portugal 9 (0.26%) 2 (0.07%) 1 (0.04%) 1 (0.04%) 1 (0.08%)Romania 24 (0.70%) 17 (0.61%) 3 (0.12%) 32 (1.41%) 11 (0.89%)Saudi Arabia 1 (0.03%) - - 1 (0.04%)

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Table 5Continued

Excerpts IndexMedics Medicus Pascal MRZ GMAJ

Country Number (%) Number (%) Number (%) Number (%) Number (%)

Senegal 2 (0.06%) - - 7 (0.27%) _ - - -Singapore 3 (0.09%) 3 (0.11%) 1 (0.04%) 1 (0.04%)South Africa 9 (0.26%) 5 (0.18%) 3 (0.12%/o) 5 (0.22%) 2 (0.16%)Spain 65 (1.90%) 23 (0.83%) 10 (0.39%) 14 (0.62%) 12 (0.97%)SriLanka - - 1 (0.04%) 1 (0.04%)Sudan 1 (0.03%)Sweden 32 (0.93%) 42 (1.51%) 32 (1.25%) 25 (1.10%) 32 (2.58%)Switzerland 117 (3.41%) 148 (5.32%) 150 (5.85%) 98 (4.32%) 58 (4.68%)Taiwan 9 (0.26%) 6 (0.22%) 1 (0.04%)Thailand 5 (0.15%) 3 (0.11 %) 2 (0.08%) - - - -Togo - - - - 1 (0.04%) - - - -Tunisia 2 (0.06%) 2 (0.07%) 5 (0.19%) 1 (0.04%) 1 (0.08%)Turkey 14 (0.41%) 2 (0.07%) - - 1 (0.04%)United Arab Emirates 1 (0.03%)United States 981 (28.61%) 977 (35.12%) 888 (34.58%) 507 (22.35%) 270 (21.79%)Upper Volta - - - - 1 (0.04%)Uruguay - - 2 (0.07%) 1 (0.04%) - - 1 (0.08%)U.S.S.R. 73 (2.13%) 79 (2.84%) 18 (0.70%) 265 (11.68%) 19 (1.53%)Venezuela 6 (0.17%) 3 (0.11%) 3 (0.12%) 1 (0.04%)Vietnam - - - - 1 (0.04%) 1 (0.04%)Yugoslavia 22 (0.64%) 15 (0.54%) - - 13 (0.57%) 7 (0.56%)Zaire - - - - 1 (0.04%)Zambia 1 (0.03%) 1 (0.04%) 1 (0.04%)Zimbabwe 1 (0.03%) 1 (0.04%) 1 (0.04%) 1 (0.04%)

Subtotal 1* 2,559(74.63%) 2,119(76.17%) 2,182(84.97%) 1,481 (65.30%) 947(76.43%)Subtotal 2t 3,101 (90.43%) 2,571 (92.42%) 2,412 (93.93%) 2,091 (92.20%) 1,175 (94.83%)Subtotal 3t 79 (2.30%) 47 (1.69%) 77 (3.00°/) 35 (1.54%) 8 (0.65%)Subtotal 4§ 25 (0.73%). 14 (0.50%) 36 (1.40%) 8 (0.35%) 4 (0.32%)Subtotal 5** 62 (1.81%) 47 (1.69%) 21 (0.82%) 10 (0.44%) 6 (0.48%)Total 3,429 (1000/c) 2,782 (100%) 2,568 (1000/c) 2,268 (100%) 1,239 (100%)Number of countriescovered 72 64 77 46 41

* France, Great Britain, Italy, Japan, Netherlands, Switzerland, United States, West Germany.t Australia, Austria, Belgium, Canada, Czechoslovakia, Denmark, East Germany, France, Great Britain, India, Italy, Japan, Netherlands, Poland, Spain, Sweden,Switzerland, United States, U.S.S.R., West Germany.t Latin America.§ Africa."Arab countries, China, Indonesia, Korea, Mongolia, Taiwan, Turkey, Vietnam.

Given the development of online search capabilitiesin which several databases can be reviewed simul-taneously, there is an objective necessity to diminishoverlap and increase coverage through cooperativeagreements on serials covered.

The quality of biomedical databases can be char-acterized by the following indices:* the total number of biomedical serials covered* the number and percentage of periodicals of theeight major western countries* the number and percentage of serials of twentydeveloped nations* the number and percentage of serials from LatinAmerica

* serials from African countries* serials from Arab countries* the total number of countries covered* the number of serials from the country in whichthe database is issued* the total number of abstracts or citations in thedatabase (Table 7)* the coverage of available literature

Table 6Unique and overlapping citations

Title % unique

Bibliography of DevelopmentalMedicine and Child Neurology 15%Tropical Diseases Bulletin 20%Ophthalmic Uterature 21.1%Helminthological Abstracts 22.1%

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Table 7Contents of major databases

AbstractsTitle or citations

Index Medicus 310,000Excerpta Medica 276,930PASCAL Explore 290,783GMAJ (German Medical Abstract Journals) 83,602Meditsinskaya Referativnyi Zhumal 48,777

* the journal title overlap or overlapfound in two databases

in references

* the percentage of unique references found after thereview of all available literature.

ACKNOWLEDGMENTS

Thanks to Dr. Martine Panneciere (responsable desbases de donnees biomedicales, CNRS) for providingPASCAL M Abstracted Serials 1987 and to Aletha A.Kowitz (director of the Bureau of Library Services,American Dental Association) for providing lists ofdental journals received by the bureau for 1983-1990.The author also wishes to thank Irwin H. Pizer andother editorial staff for their enormous work in therevision of this manuscript.

REFERENCES

1. MYCHKO-MEGRIN AY. Estimates of the annual number ofprinted scientific works on medicine in the world. Moscow,1986. 17 p. [In Russian]. A manuscript deposited in theVNIIMI (USSR) N 12251-86. Abstracted in MeditsinskayaReferativnyi Zhurnal XVI, 30(12):47, citation number 3224,Dec 1986.t

1t4 Copies of deposited manuscripts can be requested from theDepartment of Deposited Manuscripts, State Central ScientificMedical Library, Krasikova st. 30, Moscow, U.S.S.R. 117418.

2. MYCHKO-MEGRIN AY. Estimates of the annual total num-ber of titles on medicine and its disciplines and scientificproductivity of physicians. Scientometrics 1990 May-Jun;18(5-6):375-88.3. MYCHKO-MEGRIN AY. Medical information and its retriev-al. Moscow: Central Institute for Advanced Medical Train-ing, 1970. 18 p. 02NLM:FF5555.4. SNOW B, IFSHIN SL. Online database coverage of forensicmedicine. Online 1984 Mar;8(2):37-43.5. BAWDEN D, BROCK AM. Chemical toxicology searching: acomparative study of online databases. J Chem Inf ComputSci 1985 Feb;25(1):31-5.6. MoRi H. Case study: a comparative study of four data-bases; RINGDOC (UBD), BIOSIS, MEDLINE, and EM forthe search of drug-interaction. J Jap Doc Sci 1986;36(4):173-81 [In Japanese].7. TONOSAKI M. Comparison of literature on suicide pre-vention among EMBASE, Health Care and Administration,MEDLINE and PsycINFO in the Colleague system. OnlineKensaku 1986;7(2):75-80.8. MYCHKO-MEGRIN, 1986, op. cit.9. MYCHKO-MEGRIN AY. A comparative evaluation of bio-medical databases. Part 1. Cross section. Moscow, 1987, 15p. [In Russian]. A manuscript deposited in the VNIIMI(USSR) N 13517-87. Abstracted in Meditsinskij Refera-tivnyi Zhurnal XVI,31(12):39-40, citation number 3109, Dec1987.10. IBID.11. IBID.12. MYCHKO-MEGRIN AY. Chinese scientific and biomedicalliterature and its coverage in international bibliographicand abstracting services. Chin Med J 1987 Apr;100(4):335-7.13. AKAHo E, BANDAI A, FujII M. Comparison of manualand online searches of Chemical Abstracts. J Chem Inf Com-put Sci 1986 Apr;26(2):59-63.14. MIKHAILOV SS, MYCHKO-MEGRIN AY. Dental literatureand its coverage in bibliographic and abstract services. Mos-cow, 1986, 16 p. [In Russian]. A manuscript deposited inthe VNIIMI (USSR) N 12569-97. Abstracted in Meditsin-skij Referativnyi Zhurnal XVI, 31(4):58, citation number1073, Apr 1987.15. CROWLESMrrH I. Personal communication, Nov 22, 1988.

Received December 1989; accepted December 1990

Bull Med Libr Assoc 79(3) July 1991308