U.S. National Archives
Very extensive records holdings from all nations, including captured German and other European documents.
International Council of Museums
A non-governmental organization maintaining formal relations with UNESCO and serving as consultants to the United Nations Economic and Social Council. Excellent links to news about trade in illicit goods.
Association of Art Museum Directors
Provides information on a broad variety of topics involving collections in the United States, Mexico and Canada.
Central Registry of Information on Looted Cultural Property 1933-1945
A central repository of information.
Reunion des musées nationaux
Complete inventory of all the holdings of museums in France. English version. Free, but compulsory registration for use.
FBI Art Theft Program
An extremely comprehensive and interesting site.
Art Loss Register
The world's largest database of stolen art.