APA (7th ed.) Citation

Brunner, J., & Anderson, P. (1959). Threshold of eternity. Ace Books.

Chicago Style (17th ed.) Citation

Brunner, John, and Poul Anderson. Threshold of Eternity. New York: Ace Books, 1959.

MLA (9th ed.) Citation

Brunner, John, and Poul Anderson. Threshold of Eternity. Ace Books, 1959.