IndexCat is a digitized version of the printed Index-Catalogue of the Library of the Surgeon General's Office. The content and coverage is the same as the printed catalog. See: About Index-Catalogue. IndexCat also reflects the same publishing patterns: series, volumes, references, and the original dictionary arrangement for browsing and display. As a digitized resource, however, search access is not limited to the dictionary arrangement. Users may search all descriptive information as direct search terms. Content: IndexCat contains over 4.5 million online references to over 3.7 million bibliographic items.* 2.5 million items are primarily journal articles; 250,000 items are monographs (books, pamphlets, and reports); approximately 300,000 items are dissertations (theses); and 16,000 are journal titles. Series 1 and Series 2 include portraits as separate citations but Series 3, 4, and 5 indicate portraits in descriptive notes for monographs and dissertations. Coverage: IndexCat covers material from Antiquity through 1950 imprints. As in the printed series, Series 4 of IndexCat is incomplete. It includes citations printed only in the first half of the alphabet from A-Mn. The last half was never published. Therefore, if the first word of a name, title, or subject heading with its related journal articles file after Mn, they are not available. Series 5 excludes journal articles; the primary coverage is monographs, dissertations, and pamphlets with 1950 imprints or earlier. NLM will not add new bibliographic citations to IndexCat since its purpose is to reflect the bibliographic coverage of the printed Index-Catalogue.