As a Background Source
The purpose of an encyclopedia is to provide basic information about a topic. Within the article, you should encounter important terms, the names of notable people, and background information on the topic. This can help you establish a foundation for your research.
Never Cite an Encyclopedia Article
Generally speaking, you don't want to cite an encyclopedia in a college level paper or research project. Most citations provided at the end of an entry in an encyclopedia are ones that would be appropriate to cite (if you make use of them).
Use the Bibliography at the End of an Article
Sources included are considered classic books and articles on the topic.
Routledge Encyclopedia of Philosophy
B51 R68 1998
The Cambridge Dictionary of Philosophy
B41 C35 1995
Encyclopedia of Indian Philosophies
Guide to Buddhist Philosophy
B162 I52 1985
The Encyclopedia of Enlightenment
REF B802 W48 1996
The Handbook of Western Philosophy
B804 H17 1988