WorldCat
A very large union catalog that includes most libraries in the U.S. This is the free version.
Digital Public Library of America
Access to digitized documents, images, recordings, etc. from libraries, archives, and museums.
Catalog of U.S. Government Publications
Index of U.S. government publications, 1976 - present.
LibDex
A worldwide directory of library catalogs.
(Note: Except for the Castleton Public Library, you may place an interlibrary loan request at any of the following libraries by using the "Multiple Library Search" feature of the Calvin Coolidge Library Catalog.)
Castleton Public Library
Dartmouth College
Library of Congress
Middlebury College
Norwich University
St. Michael's College
University of Vermont
Vermont Archives