Kaufmann, W. J. (1999). Universe (5th ed.). New York: W.H. Freeman.
Chicago Style aipamenaKaufmann, William J. Universe. 5th ed. New York: W.H. Freeman, 1999.
MLA aipamenaKaufmann, William J. Universe. 5th ed. New York: W.H. Freeman, 1999.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.