APA

United States, . (1990). A Directory of U.S. government depository libraries. Washington: U.S. G.P.O.

Chicago

United States, . 1990. A Directory of U.S. government depository libraries. Washington: U.S. G.P.O.

Harvard

United States, . (1990). A Directory of U.S. government depository libraries. Washington: U.S. G.P.O.

MLA

United States, . A Directory of U.S. government depository libraries. Washington: U.S. G.P.O. 1990.