APA

Peterson R. T., . (1961). A field guide to western birds. Cambridge, MA, U.S.A: Houghton Mifflin Company Boston.

Chicago

Peterson Roger Tory, . 1961. A field guide to western birds. Cambridge, MA, U.S.A: Houghton Mifflin Company Boston.

Harvard

Peterson R. T., . (1961). A field guide to western birds. Cambridge, MA, U.S.A: Houghton Mifflin Company Boston.

MLA

Peterson Roger Tory, . A field guide to western birds. Cambridge, MA, U.S.A: Houghton Mifflin Company Boston. 1961.