National Geographic Society (U.S.), Dunn, J. L., & Alderfer, J. K. (2011). National Geographic field guide to the birds of North America (Sixth edition.). National Geographic Society.
Cita Chicago Style (17a ed.)National Geographic Society (U.S.), Jon L. Dunn, y Jonathan K. Alderfer. National Geographic Field Guide to the Birds of North America. Sixth edition. Washington, D.C.: National Geographic Society, 2011.
Cita MLA (8a ed.)National Geographic Society (U.S.), et al. National Geographic Field Guide to the Birds of North America. Sixth edition. National Geographic Society, 2011.
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