APA (7th ed.) Citation

Ditmars, R. L. (1939). A Field book of North American snakes. Doubleday.

Chicago Style (17th ed.) Citation

Ditmars, Raymond L. A Field Book of North American Snakes. Garden City, New York: Doubleday, 1939.

MLA (9th ed.) Citation

Ditmars, Raymond L. A Field Book of North American Snakes. Doubleday, 1939.