APA

Darwin C., Porter D. M. & Graham P. W. (1993). The portable Darwin. New York: Penguin Books.

Chicago

Darwin Charles, Porter Duncan M and Graham Peter W. 1993. The portable Darwin. New York: Penguin Books.

Harvard

Darwin C., Porter D. M. and Graham P. W. (1993). The portable Darwin. New York: Penguin Books.

MLA

Darwin Charles, Porter Duncan M and Graham Peter W. The portable Darwin. New York: Penguin Books. 1993.