APA (7th ed.) Citation

Van Vogt, A. E., & Conklin, G. (1969). The world of Null-A. Dobson.

Chicago Style (17th ed.) Citation

Van Vogt, A. E., and Groff Conklin. The World of Null-A. London: Dobson, 1969.

MLA (8th ed.) Citation

Van Vogt, A. E., and Groff Conklin. The World of Null-A. Dobson, 1969.