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.
Academic Search Premier (date coverage varies)
Full-text articles from over 3,600 journals in the social sciences, arts and humanities, and sciences.
Historical Abstracts with Full Text (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 Newspapers Collection, Hartford Courant, Los Angeles Times, New York Amsterdam News, New York Times, South China Morning Post, Times of India, and Washington Post.
LexisNexis Academic (date coverage varies)
Full-text federal and state laws, international legal materials, and law reviews. Also newspapers and business information.
PAIS Index (1972 to present)
Coverage of articles, selected books, government documents, research reports, etc., from a wide range of social sciences.
Readers Guide Retrospective (1890-1984)
Provides indexing of general-interest periodicals published in the United States during the 20th century.
Standard general encyclopedia.
Gale Virtual Reference Library
70 reference e-books, including multivolume works like the Encyclopedia of Religion, American Decades, and more.
Digitized entries from Oxford's Dictionaries, Companions and Encyclopedias, spanning multiple subject areas.
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)
Twentieth Century Britain, An Encyclopedia. N.Y., Peter Lang, 2002. Revised edition.
Brief entries on people, places, weaponry, etc., with little bibliographies. (Ref DA 566 T835 2002)
Dictionary of Twentieth Century Culture: French Culture 1900-1975. Detroit, Gale, 1995.
Short entries on people, art movements, culrual events, etc. (Ref DC 33.7 F726 1995)
Encyclopedia of Eastern Europe, from the Congress of Vienna to the Fall of Communism. N.Y., Garland, 2000.
Short and longer entries on places, events, prominent individuals. (Ref DJK 6 E53 2000)
Historical Dictionary of the Spanish Civil War, 1936-1939. Westport CT, Greenwood, 1982.
Alphabetically-arranged entries on people, places, topics, etc., with brief bibliographies. (Ref DP 269 H54 1982)
Encyclopedia of the Holocaust. N.Y., Macmillan, 1990; 4 volumes.
Entries on camps, events, individuals, etc., with some maps and photos, and very brief bibliographies. (Ref D 804.3 E53 1990)
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)
Links to style manuals...the Library's Citing Sources page.