Cita APA (7th ed.)

Worrall, L. (1990). Geographic information systems: Developments and applications. Belhaven Press.

Cita Chicago (17th ed.)

Worrall, Les. Geographic Information Systems: Developments and Applications. London ; New York: Belhaven Press, 1990.

Cita MLA (9th ed.)

Worrall, Les. Geographic Information Systems: Developments and Applications. Belhaven Press, 1990.