APA (7th ed.) Citation

Ryder, J. P. (1993). Ring-billed gull: Larus delawarensis. American Ornithologists' Union ; The Academy of Natural Sciences.

Chicago Style (17th ed.) Citation

Ryder, John Pemberton. Ring-billed Gull: Larus Delawarensis. Washington, D.C. : Philadelphia, PA: American Ornithologists' Union ; The Academy of Natural Sciences, 1993.

MLA (9th ed.) Citation

Ryder, John Pemberton. Ring-billed Gull: Larus Delawarensis. American Ornithologists' Union ; The Academy of Natural Sciences, 1993.