The Philosophy of Science: An Encyclopedia.
(online; print version: Olin Reference Q 174.7 .P45 2006)
Find articles on all aspects of the philosophy of science including biographical articles on philosophers of science.
Encyclopedia of philosophy and the social sciences.
It is not only about the philosophy of the social sciences but, going beyond that, it is also about the relationship between philosophy and the social sciences (publisher).
Routledge Encyclopedia of Philosophy Online.
(online; print version: Olin Reference B 51 .R68 1998)
Find articles on philosophers and philosophical topics. Strong coverage in ethics. Online version regularly updated.