APA

Keene C. I., Grassy J., . (1998). National Audubon Society first field guide: mammals. New YorK: Scholastic.

Chicago

Keene Chuck I, Grassy John, . 1998. National Audubon Society first field guide: mammals. New YorK: Scholastic.

Harvard

Keene C. I., Grassy J., . (1998). National Audubon Society first field guide: mammals. New YorK: Scholastic.

MLA

Keene Chuck I, Grassy John, . National Audubon Society first field guide: mammals. New YorK: Scholastic. 1998.