APA (7th ed.) Citation

Hoffman, S. (1955). An Index to Unknown and Unknown worlds. Sirius Press.

Chicago Style (17th ed.) Citation

Hoffman, Stuart. An Index to Unknown and Unknown Worlds. Black Earth, Wis.: Sirius Press, 1955.

MLA (9th ed.) Citation

Hoffman, Stuart. An Index to Unknown and Unknown Worlds. Sirius Press, 1955.

Warning: These citations may not always be 100% accurate.