It's important to cite your sources accurately. JSTOR can help - each book chapter and article on the site includes a "Cite this item" link. Select the option, and you will see a new window with a preformatted citation, in MLA, APA, and Chicago styles.
The preformatted citations on JSTOR are updated as the style rules change, but it's always a good idea to double check before submitting your final paper.