APA

Gavin C. I., . (1964). The fortress. New York: Doubleday.

Chicago

Gavin Catherine Irvine, . 1964. The fortress. New York: Doubleday.

Harvard

Gavin C. I., . (1964). The fortress. New York: Doubleday.

MLA

Gavin Catherine Irvine, . The fortress. New York: Doubleday. 1964.