Check-list of North American birds /
prepared by a committee of the American Ornithologists' Union.

APA Citation

American Ornithologists' Union. (1931). Check-list of North American birds. 4th ed., constituting the "Systema avium" for North America north of Mexico. Lancaster, Pa.: American Ornithologists' Union.

MLA Citation

American Ornithologists' Union. Check-list of North American Birds. 4th ed., constituting the "Systema avium" for North America north of Mexico. Lancaster, Pa.: American Ornithologists' Union, 1931.