APA

Proctor R. A., . (1902). Other worlds than ours. New York: P.F. Collier and son.

Chicago

Proctor Richard A, . 1902. Other worlds than ours. New York: P.F. Collier and son.

Harvard

Proctor R. A., . (1902). Other worlds than ours. New York: P.F. Collier and son.

MLA

Proctor Richard A, . Other worlds than ours. New York: P.F. Collier and son. 1902.