APA

Commerce Clearing House, . (1968). 1968 Government contracts guide. New York: CCH.

Chicago

Commerce Clearing House, . 1968. 1968 Government contracts guide. New York: CCH.

Harvard

Commerce Clearing House, . (1968). 1968 Government contracts guide. New York: CCH.

MLA

Commerce Clearing House, . 1968 Government contracts guide. New York: CCH. 1968.