Cita APA (7th ed.)
Lewis, C. (1956). The problem of pain (1 a. ed.). Georffrey bles.
Cita Chicago (17th ed.)
Lewis, C.S. The Problem of Pain. 1 a. ed. Londres: Georffrey bles, 1956.
Cita MLA (9th ed.)
Lewis, C.S. The Problem of Pain. 1 a. ed. Georffrey bles, 1956.
Atenció: Aquestes cites poden no estar 100% correctes.