Cita APA (7th ed.)

BONNER, W. N. (1990). The natural history of seals. Facts on File.

Cita Chicago (17th ed.)

BONNER, W. Nigel. The Natural History of Seals. New York: Facts on File, 1990.

Cita MLA (9th ed.)

BONNER, W. Nigel. The Natural History of Seals. Facts on File, 1990.