Work on the ISTC began in 1980 under the leadership of the British Library's Lotte Hellinga. Frederick R. Goff's "Incunabula in American Libraries" (1973) was the first pre-existing catalog to be keyed into ISTC's database. Besides providing the catalog's first 12,900 entries, Goff's system for classifying information about incunables formed the basis for the structure of ISTC's records. Entries for all of the incunables in British Library and the Italian union catalog (IGI) were added next, followed by other national incunable catalogs.