Peterson, R. T. (1956). A fiels guide to the birds (2ª ed.). Houghton Miffin Company.
Chicago-viite (17. p.)Peterson, Roger Tory. A Fiels Guide to the Birds. 2ª ed. Houghton Miffin Company, 1956.
MLA-viite (9. p.)Peterson, Roger Tory. A Fiels Guide to the Birds. 2ª ed. Houghton Miffin Company, 1956.
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