APA (7th ed.) Citation

Abell, G. O., & Morrison, D. (1991). Exploration of the universe (6th ed.). Saunders College Publishing.

Chicago Style (17th ed.) Citation

Abell, George O., and David Morrison. Exploration of the Universe. 6th ed. Philadelphia: Saunders College Publishing, 1991.

MLA (9th ed.) Citation

Abell, George O., and David Morrison. Exploration of the Universe. 6th ed. Saunders College Publishing, 1991.