IndexCat is the online Index-Catalogue of the Library of the Surgeon-General's Office, (Index-Catalogue), printed from 1880 - 1961 in five (5) series consisting of sixty-one (61) volumes. The Index-Catalogue was initiated by John Shaw Billings who was the principal indexer for Series I.1 Billings expanded the Library of the Surgeon-General's Office into a major medical and scientific collection and created Index Medicus as well as the Index-Catalogue - each a cornerstone for the foundation of the National Library of Medicine (NLM).