APA

Pyle P., Howell S. N. G., . (1997). Identification guide to North American birds. Bolinas (California, EE. UU.): Slate Creek Press.

Chicago

Pyle Peter, Howell Steve N G, . 1997. Identification guide to North American birds. Bolinas (California, EE. UU.): Slate Creek Press.

Harvard

Pyle P., Howell S. N. G., . (1997). Identification guide to North American birds. Bolinas (California, EE. UU.): Slate Creek Press.

MLA

Pyle Peter, Howell Steve N G, . Identification guide to North American birds. Bolinas (California, EE. UU.): Slate Creek Press. 1997.