Finding Secondary Sources
Historical Abstracts (1954- ) includes books, book chapters, journal articles (but not book reviews) for non-North American history, 1450-date.
PERSEE is the French equivalent of JSTOR, providing full text from their inceptions to 5 years ago. The word "scientific" means "scholarly" here.
JSTOR offers full-text of complete runs (up to about 5 years ago) of over 400 journals. Allows simultaneous or individual searching, full-text searching optional. Use Advanced Search.
Web of Science Citation Indexes allow citation searching, that is, starting with an article of interest and finding more recent articles that have cited it. More information.