Bernhardsen, T. (1999). Geographic information systems: An introduction (2nd ed.). John Wiley.
Chicago Style aipamenaBernhardsen, Tor. Geographic Information Systems: An Introduction. 2nd ed. New York: John Wiley, 1999.
MLA aipamenaBernhardsen, Tor. Geographic Information Systems: An Introduction. 2nd ed. John Wiley, 1999.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.