Warren, E. R. (1908). Warren on Birds of Northwestern Colorado. Zenodo.
Cita Chicago (17th ed.)Warren, Edward Royal. Warren on Birds of Northwestern Colorado. Zenodo, 1908.
Cita MLA (9th ed.)Warren, Edward Royal. Warren on Birds of Northwestern Colorado. Zenodo, 1908.
Atenció: Aquestes cites poden no estar 100% correctes.