APA

Clark R. J., . (1975). A field study of the short-eared owl, asio flammeus (pontoppidan), in North America. Bethesda, Maryland, United States: The Wildlife Society.

Chicago

Clark Richard J, . 1975. A field study of the short-eared owl, asio flammeus (pontoppidan), in North America. Bethesda, Maryland, United States: The Wildlife Society.

Harvard

Clark R. J., . (1975). A field study of the short-eared owl, asio flammeus (pontoppidan), in North America. Bethesda, Maryland, United States: The Wildlife Society.

MLA

Clark Richard J, . A field study of the short-eared owl, asio flammeus (pontoppidan), in North America. Bethesda, Maryland, United States: The Wildlife Society. 1975.