APA

Snow D. W., Snow B. K., . (1964). Breeding seasons and annual cycles of Trinidad land-birds. [New York: New York Zoological Society.

Chicago

Snow D W, Snow B K, . 1964. Breeding seasons and annual cycles of Trinidad land-birds. [New York: New York Zoological Society.

Harvard

Snow D. W., Snow B. K., . (1964). Breeding seasons and annual cycles of Trinidad land-birds. [New York: New York Zoological Society.

MLA

Snow D W, Snow B K, . Breeding seasons and annual cycles of Trinidad land-birds. [New York: New York Zoological Society. 1964.