APA

Cairns D. S., . (1937). The riddle of the world. London: Student Christian movement press.

Chicago

Cairns D S, . 1937. The riddle of the world. London: Student Christian movement press.

Harvard

Cairns D. S., . (1937). The riddle of the world. London: Student Christian movement press.

MLA

Cairns D S, . The riddle of the world. London: Student Christian movement press. 1937.