The number of history reference works has proliferated at a tremendous rate in the past few decades. The effective use of these tools is one of the most important research skills of the historian. Bibliographies should be understood as more than just books that list books. The design and workings of these tools are meant to influence search strategies and research methods. This document provides an overview to the use of bibliographic resources in the field of U.S. history. An essay describes the various types of historical reference works available to the historian and how these tools are best utilized. A taxonomy of reference works in U.S. history also is provided; this is a listing of important reference works that are organized into the various reference work categories that are discussed in the essay. One hundred thirty-one resources, organized into 24 categories, are listed in the taxonomy. (DB)