Bernhardsen, T. (1999). Geographic information systems: An introduction (2nd ed.). Wiley.
Cita Chicago (17th ed.)Bernhardsen, Tor. Geographic Information Systems: An Introduction. 2nd ed. New York: Wiley, 1999.
Cita MLA (9th ed.)Bernhardsen, Tor. Geographic Information Systems: An Introduction. 2nd ed. Wiley, 1999.
Atenció: Aquestes cites poden no estar 100% correctes.