Now that the Social Science Citation Index (SSCI) and the Arts and Humanities Citation Index (AHCI) are on compact disc, these bibliographic tools have come into their full usefulness. The print versions of these were made possible by the development of computer technology in the 1950s, but they were always rather cumbersome to use. For one thing, extensive use requires moving from volume to volume (i.e., from the citation volumes to the source volumes) and for subjects, from the Permuterm Subject Index as well. Moreover, the print is very small. Even with multivolume five- and ten-year accumulations, the array of multicolored heavy volumes wedged into a sagging shelf has presented a daunting challenge to all but the most diligent researcher.

To read the instruction manual was to court despair when coming across such mystifying sentences as: "ARRANGEMENT. Since every significant word in the title of an item is paired with every other significant word, one of these words becomes a primary term, the other a co-term listed under the primary term."

Now the instructions are simple, and a search that would have taken hours in the print version takes seconds on the CD-ROM version. And you can print the results, or, even better, download them onto a floppy disk for use in your own computer.

The concept of the citation index is really simple: it is a listing of articles and books by author and title showing where they have been cited. (A recent upgrade of the SSCI includes abstracts from January 1992.) For instance, it allows you to find recent articles that have cited Thomas Kuhn's Structure of Scientific Revolution. You may also find articles that have cited both Kuhn and Peter Novick's That Noble Dream. In doing a subject search on the MLA compact disc, you might come across the work of Marjorie Garber and want to find other articles that approach Shakespeare in a similar fashion. A citation search in the AHCI will find articles that have quoted Marjorie Garber. A search in ERIC, a database in HOLLIS, for discussions of the Carnegie Foundation for the Advancement of Teaching special report, Scholarship Reconsidered, will find articles on similar topics, but you will not know if they mention that report until you find the article. A search in the 1992 SSCI turns up 19 references to that book. A look at the other references in those articles will tell which ones are worth your while to track down.

The citations in a large number of journals are indexed by these two products. The SSCI covers 1,400 journals spanning 50 disciplines in the social sciences, and it adds 125,000 items per year. The AHCI covers 1,100 journals in 25 disciplines, and it adds more than 100,000 items each year. Both indexes include relevant items from the journals indexed by the Science Citation Index. Every significant item in those journals is indexed, including letters, notes, corrections, and editorials.

Along with the three major search fields in these indexes—title word, author, and citation—you may also search for the address of an author of an article. It is also possible to search by journal title, which will give you the table of contents for the period covered by the disk.

One thing from the print version has remained the same in the CD-ROM version: citations may be inconsistent. The Thomas Kuhn work mentioned above appears in six different ways. The electronic version does have a dictionary that you can browse to select all the variants.

Subject searching is done by using title words. There are no subject headings supplied by editors. It is advisable to keep the searches broad and to use as many synonyms as possible. A retrieved record from a search gives the author, title, and publication information. It also gives the number of cited references in that article. You may call up a list of those references on the screen and select articles for further searching from the list of citations. Each selected citation becomes a searchable set, and you may return to the search screen at any time to see who has cited those articles. It is possible to combine the sets to find articles that have cited a combination of the articles you may be interested in, as in the Kuhn and Novick example above.

The retrieved record also gives the number of related records. A related record is one that shares one or more citations with the record you are viewing. It is possible to view each of the related records, each of which in turn gives the cited references, other related records, and, in a separate category, a listing of the citations that are shared. The cited references and the shared references may be selected for further searching. It is possible to follow a trail of related records up to five levels, i.e., the related records of related records.

For example, let us suppose the citation you are viewing has 20 related records. One citation of that 20 may have 15 related records, and one of the 15 may have 22. The system allows you to view the cited references and all 57 related records. And you would still have two more levels of related records to go.

Because of the speed and ease with which periodical indexes retrieve information, they tend to produce an excess of results. The time saved in finding the citations of articles can become lost looking for, and judging, the large number of articles retrieved. Citation indexes help with this problem. Because you can view the article's bibliography, you are in a much better position to judge the worth of an article for your purposes without tracking it down.

The results of your search can be printed or saved on a 3.5 inch floppy disk. You can print or save one record at a time or all of the results of a search, or you may collect individual records from your various searches as you review them and print or download them at the end of your session.

In printing/saving a search, you have the option of printing the references as well. As some records may have hundreds of citations, we urge you, if you need the article's references, to be prepared to download them. The printing can take a very long time.

Both the SSCI and the AHCI are contained on six separate disks. It is possible to save your search strategy while you change from disk to disk. Again you need a formatted disk.

For those whose fields of study are covered by these indexes, saving your search strategy is an advantage. It is possible to build a personalized database and update it quarterly. You can limit the saved strategy to just search the latest update.

The SSCI and the AHCI are very user-friendly. A menu at the bottom of the screen gives you all the commands available at each screen. The context-sensitive help screens are quite useful and a complete index of help screens is readily available.

The citation indexes are produced by the Institute for Scientific Information, 3401 Market St., Philadelphia, PA 19104. (800) 336-4474, ext. 1321.

—Kevin Donnelly is a research librarian at the Widener Library of Harvard University. An earlier version of this article appeared in the Harvard Library Research Forum.