APA
U.S. Department of Agriculture, . (1968). Preferential trade arrangements of foreign countries. Washington, D.C: U.S. Department of Agriculture.
Chicago
U.S. Department of Agriculture, . 1968. Preferential trade arrangements of foreign countries. Washington, D.C: U.S. Department of Agriculture.
Harvard
U.S. Department of Agriculture, . (1968). Preferential trade arrangements of foreign countries. Washington, D.C: U.S. Department of Agriculture.
MLA
U.S. Department of Agriculture, . Preferential trade arrangements of foreign countries. Washington, D.C: U.S. Department of Agriculture. 1968.