The Architect's Library. "Notable Books on Architectural Themes in the Vassar College Lib
Art Canada Institute Online Books. E-books on Canadian art.
Art Resources from the Mid-20th Century: Digitized Highlights from the Collections of Hilla Rebay and Juliana Force. Collaborative project on the Internet Archive, by the Solomon R. Guggenheim Museum and the Whitney Museum of American Art.
Association of Architecture School Librarians Core Reference List. Libguide to the most important books in many areas relating to architectural research.
British Library Illustrations digitized from 17th, 18th, and 19th century books. On Flickr Commons for "anyone to reuse, remix, or repurpose."
Catalogues raisonnes. Essay about the medium and links to online resources, from the ARLIS News-sheet, 2012.
Constructing the Study of Islamic Art by Oleg Grabar. Full text of four volume set available online at Archnet.
Descriptive Cataloging of Rare Materials (Graphics). Free, online book of guidelines updated by the Library of Congress and the Association of College and Research Libraries.
Designers and Books. Site dedicated to "books that inspire creativity, innovation, and invention."
Getty Publication Virtual Library. Free access to selected Getty publications.
Goethe's Theory of Colors. Full text of 1840 available on the Internet Archive.
Historical trade catalogs from the Winterthur Museum Library on the Internet Archive.
History of Cartography. Free online pdf version of the first three volumes of this set published by the University of Chicago Press.
World Digital Library. Free access to "significant primary materials from countries and cultures around the world."