Παραπομπή APA

Sagan, C., & Leonard, J. N. (1967). <Planets>. Time life books.

Παραπομπή Chicago Style

Sagan, Carl, και Jonathan Norton Leonard. <Planets>. New York: Time life books, 1967.

Παραπομπή MLA

Sagan, Carl, και Jonathan Norton Leonard. <Planets>. Time life books, 1967.