Peking Bookhouse 1520 Sherman Ave. But find is the operative word. The store is unorganized, so allow plenty of time to browse the shelves.
Literature is in one section, but the social science materials are scattered about.
Also of related interest is the basement. PBH's basement is full of Chinese language items, most from the Cultural Revolution period. Mao buttons, red books, prints, and pamphlets abound. C.C. Cheng is a great guy. If you're in the Chicago area, a visit to Peking Bookhouse is a must.