APA

Wallace G. J., Mahan H. D., . (1975). An introduction to ornithology. New York: Macmillan.

Chicago

Wallace George John, Mahan Harold D, . 1975. An introduction to ornithology. New York: Macmillan.

Harvard

Wallace G. J., Mahan H. D., . (1975). An introduction to ornithology. New York: Macmillan.

MLA

Wallace George John, Mahan Harold D, . An introduction to ornithology. New York: Macmillan. 1975.