APA

Lewis C. S., . (1951). The Screwtape letters. London :9: Geoffrey Bles.

Chicago

Lewis C S, . 1951. The Screwtape letters. London :9: Geoffrey Bles.

Harvard

Lewis C. S., . (1951). The Screwtape letters. London :9: Geoffrey Bles.

MLA

Lewis C S, . The Screwtape letters. London :9: Geoffrey Bles. 1951.