The open-access Stanford Encyclopedia of Philosophy is widely used as the go-to reference work among philosophers.
The open-access Internet Encyclopedia of Philosophy (IEP) began in 1995 as a non-profit with the goal of providing detailed, scholarly information on a wide range of important topics and philosophers in all areas of philosophy. Entries are written by identified philosophers.
Fred Rowland, the Philosophy Librarian at Temple University Libraries, created and vetted this list. It has been reproduced here with his permission. Thank you, Fred!