card index
n.
References or short citations to materials, with each item described separately on a card (or cards), and arranged to facilitate access.
Notes
A card index may be distinguished from a catalog by the amount of description. An index may indicate only the location of potentially relevant material, and the usefulness of the material references can be determined only by direct examination of the material. The use of separate cards for each item facilitated the interfiling of new or corrected entries and the removal of obsolete entries.
