Worrall, L. (1990). Geographic information systems: Developments and applications. Belhaven Press.
Chicago-viite (17. p.)Worrall, Les. Geographic Information Systems: Developments and Applications. London ; New York: Belhaven Press, 1990.
MLA-viite (9. p.)Worrall, Les. Geographic Information Systems: Developments and Applications. Belhaven Press, 1990.
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