Longman Dictionary of Contemporary English
card index
noun
EXAMPLES FROM CORPUS
▪ For instance, he collects on his little card index all references in Wells to feeding, eating, and patent medicines.
▪ His job was to make a card index of suspect radicals - anyone who wrote or talked against government.
▪ Once inside they went to the card index.
▪ Telephone numbers can be kept separately, on a card index or in a contact book.
▪ The reports are indexed by subject and location as appropriate on a card index.
▪ This computerised index replaced a card index system that used to have to be updated by hand by bureaux staff.
▪ Within a file, information is organized in a number of records, rather like the cards in a card index.