Peterson, R. T. (1956). A fiels guide to the birds (2ª ed.). Houghton Miffin Company.
Lua i Stíl Chicago (17ú heag.)Peterson, Roger Tory. A Fiels Guide to the Birds. 2ª ed. Houghton Miffin Company, 1956.
Lua MLA (9ú heag.)Peterson, Roger Tory. A Fiels Guide to the Birds. 2ª ed. Houghton Miffin Company, 1956.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.