Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2021). "Owls". IOC World Bird List Version 11.1. International Ornithologists' Union. Retrieved 22 May 2021.
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Peterson, Roger Tory, 1908-1996. (1990). A Field Guide to Western Birds. Peterson, Virginia Marie, 1925-, National Audubon Society., National Wildlife Federation., Roger Tory Peterson Institute. (Third edition, completely revised and enlarged ed.). Boston: Houghton Mifflin Company. p. 204. ISBN0-395-51424-X. OCLC19511450.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)