APA

Martin B., Carl E., . (2007). Polar Bear, Polar Bear, What Do You Hear?. London: Puffin books.

Chicago

Martin Bill, Carl Eric, . 2007. Polar Bear, Polar Bear, What Do You Hear?. London: Puffin books.

Harvard

Martin B., Carl E., . (2007). Polar Bear, Polar Bear, What Do You Hear?. London: Puffin books.

MLA

Martin Bill, Carl Eric, . Polar Bear, Polar Bear, What Do You Hear?. London: Puffin books. 2007.