Improvement of the selectivity of citation indexes to science literature through inclusion of citation relationship indicators

Abstract Citation indexes to large bodies of science literature can often list far more citing references under the known cited reference than the user can afford the time to look up. By providing some additional information, beyond the minimal association of the citing reference with the cited reference, a citation index could provide the means for the user to select from a long list those citing references which are most relevant to his immediate search requirement. Means of providing this selectivity are discussed. Particular attention is given to the possibility of adding short codes to the citation entries which would be informative on the way in which the citing publication is operationally related to the cited one (this method is an integral feature of the Shepard's legal citations). A scheme of citation relationships of potential value to users of science literature is presented. These relationships were tested on a sampling of physics literature. The suggested categories include indicators of the relation of the citing reference to the scientific process in general, as well as indicators of its relationship to the cited reference in particular. Assignment of the categories to a citation requires the exercise of judgment, as in subject indexing, but does not involve the use of subject terminology. An illustration is provided of the application of citation relationship indicators to an excerpt from a citation index to physics literature.