One of the best places to start research is in the Five-College Library Catalog . All books are listed by their AUTHORS, TITLES, and SUBJECTS, and you can also use the KEYWORD function to search.
To track down books by and about particular authors, use both AUTHOR and SUBJECT searching.
To identify books that contextualize your author or theme, try KEYWORD searching, but keep in mind that, in itself, such a search is not likely to yield a complete, or completely relevant, list of locally-owned books on any particular topic. Start your KEYWORD search by typing in a common language characterization of your topic, say "nazi and gypsy", then select titles from the resulting list that interest you, note which official subject headings are assigned to those titles, then click on them to do a more thorough SUBJECT search.
SUBJECT searching, as such, requires that you use the exact words or phrases libraries have chosen to describe your topic; for example, libraries list books about the Nazi treatment of gypsies under "Romanies -- Nazi Persecution" and broader coverage is under the heading "World War, 1939-1945 -- Atrocities"; note the way the subject headings are subdivided. Ask at the Reference Desk if you're not sure what words or phrases to use.
To widen your search for books beyond the Five College libraries, try WorldCat, a union catalog of thousands of libraries' holdings.
ABSEES: American Bibliography of Slavic and East European Studies (1939 to present)
Index covering North American scholarship on East-Central and Eastern Europe and the former Soviet Union.
Academic Search Premier (date coverage varies)
Full-text articles from over 3,600 journals in the social sciences, arts and humanities, and sciences.
Access World News (Newsbank) (date coverage varies)
Electronic editions of over 2,600 local, regional, and national U.S. newspapers as well as 1,500 international sources. Fully searchable and browsable by map.
Historical Abstracts (1955 to present)
Scholarly literature about world history since 1450 (excluding the United States and Canada).
Historical Newspapers (ProQuest)
Combined search of the historic Boston Globe, Chicago Defender, Chinese Newspaper Collection, Los Angeles Times, New York Amsterdam News, New York Times, Times of India, and Washington Post.
International Bibliography of the Social Sciences (IBSS) (1951 to present)
Indexes about 3,000 journals and 7,000 books per year.
LEXIS-NEXIS Academic Universe (date coverage varies)
Full-text federal and state laws, international legal materials, and law reviews. Also newspapers and business information.
Important scholarly encyclopedia for all aspects of Judaic studies.
Encyclopedia Britannica Online
Standard general encyclopedia.
Gale Virtual Reference Library
70 reference e-books, including multivolume works like the Encyclopedia of Religion, American Decades, and more.
International Encyclopedia of the Social and Behavioral Sciences
Scholarly surveys of all aspects of social sciences.
Print-format reference works
The Oxford Encyclopedia of the Modern World, 1750 to the Present. N.Y., Oxford, 2008. 8 vols.
Short and somewhat longer entries on places, events, people, etc., most with brief bibliographies (Ref D 205 O94 2008)
Europe Since 1945, An Encyclopedia. N.Y., Garland, 2001. 2 vols.
Similar to the previous item, with narrower chronological coverage. (Ref D1051 E95 2001)
Encyclopedia of European Social History from 1350 to 2000. N.Y., Scribner's, 2001. 6 volumes.
An excellent collection of essays (with short bibliographies) on major topics in European social history, including historiography, periods, regions and nations, sociology, gender, religion, etc. (Ref HN 373 E63 2001)
Modern Germany: An Encyclopedia of History, People, and Culture, 1871-1990. N.Y., Garland, 1998. 2 volumes.
Short articles, many of which have very brief bibliographies, on broad and narrow subjects, people, places, events, etc. (Ref DD 14 M64 1998)
The Simon and Schuster Encyclopedia of World War II. N.Y., S & S, 1978.
Brief entries on people, places, weaponry, etc., with maps and photos; no bibliographies. (Ref D 740 S57)
International Historical Statistics: Europe, 1750-2000. Houndmills UK, Palgrave Macmillan, 2003. 5th ed.
A large, if necessarily selective, compilation of demographic, economic, and social data. (Ref HA 1107 M5 2003)
The Times Atlas of European History. London, HarperCollins, 1994.
Detailed, full-colour maps. (Ref G 1797.21 S1 T5 1994)
Encyclopedia of the Holocaust. N.Y., Macmillan, 1990; 4 volumes.
Alphabetically-arranged entries on people, places, topics, etc., with some maps and photos, and very brief bibliographies. (Ref D 804.3 E53 1990)
Depending on your research topic, one or more of the following book-length bibliographies may be useful: The Third Reich, 1933-1945 (Ref DD 256.5 S576 1987), World War II and its Origins: A Select Annotated Bibliography of Books in English (Ref D 743 B58 1975), Bibliography on Holocaust Literature (Ref D 804.3 E32 1986 + supplement, 1990), Uncertain Judgment: A Bibliography of War Crimes Trials (Ref KZ 1168 L49 1979). To locate topical bibliographies, use the SUBJECT category in the Library Catalog, guess at KEYWORD(s), and/or ask at the Reference Desk.
Among many websites devoted to genocide and state violence more generally, with dozens or even hundreds of links to primary and secondary sources, the following are recommended: The Centre for the Study of Genocide and Mass Violence at The University of Sheffield, the University of Minnesota's Center for Holocaust and Genocide Studies (CHGS), and The Holocaust, from the University of London's Institute of Historical Research.
Links to style manuals...the Library's Citing Sources page.