APA (7th ed.) Citation

Asimov, I. (1968). The universe: From flat earth to quasar (First printing (Discus edition), 1968.). Avon.

Chicago Style (17th ed.) Citation

Asimov, Isaac. The Universe: From Flat Earth to Quasar. First printing (Discus edition), 1968. New York: Avon, 1968.

MLA (9th ed.) Citation

Asimov, Isaac. The Universe: From Flat Earth to Quasar. First printing (Discus edition), 1968. Avon, 1968.