Gaya APA

Schwarzkopf, L, C. (1990). Government reference books 88/89 : a biennial guide to U.S. government publications . Englewood, CO: Libraries Unlimited.

Gaya MLA

Schwarzkopf, LeRoy, C.. "Government reference books 88/89 : a biennial guide to U.S. government publications". Englewood, CO: Libraries Unlimited, 1990. Text.