APA (7th ed.) Citation

Sagan, C., & Leonard, J. N. 1. j. a. (1972). Planets. Time-Life Books.

Chicago Style (17th ed.) Citation

Sagan, Carl, and Jonathan Norton 1903- joint auth Leonard. Planets. New York: Time-Life Books, 1972.

MLA (9th ed.) Citation

Sagan, Carl, and Jonathan Norton 1903- joint auth Leonard. Planets. Time-Life Books, 1972.