website: Zoonomen - Zoological Nomenclature Resource, 2005.08.07; "Zoonomen Nomenclatural data" maintained by Alan P. Peterson at http://www.zoonomen.net
database: NODC Taxonomic Code;
Peters, James Lee 1945-08-13. Check-list of Birds of the World, vol. 5. Harvard University Press. Cambridge, Massachusetts, USA. xi + 306. . .
American Ornithologists' Union 1957-01-01. Check-list of North American Birds, 5th Edition. American Ornithologists' Union. Baltimore, Maryland, USA. xiii + 691. . .
Dickinson, Edward C., ed. 2003-01-01. The Howard and Moore Complete Checklist of the Birds of the World, 3rd edition. Princeton University Press. Princeton, New Jersey, USA. 1039. 0-691-11701-2. .
Weick, Friedholm 1999-12-01. Ökologie der Vögel, vol. 21, no. 2. . . 363-387. . Engl. Translation: Taxonomy of the American Great horned Owls (Bubo spp) with consideration of a mostly parallel variation within the polymorphic subspecies. With two colour plates and two distribution-maps.
Todd McConchie, ITIS Data Development Technician: The taxonomic status of Bubo virginianus algistus (Oberholser, 1904) is in question. Peters (1940), American Ornithologists' Union (1957) and Weick (1999) use the ssp. as valid. Dickinson (2003) does not include the name as valid. Zoonomen (2005) includes the name as proivisionally valid until further review is possible