Não informado. (1990). Cartography and geographic information systems. American Congress on Surveying and Mapping.
Chicago-referens (17:e uppl.)Não informado. Cartography and Geographic Information Systems. Bethesda, Md: American Congress on Surveying and Mapping, 1990.
MLA-referens (8:e uppl.)Não informado. Cartography and Geographic Information Systems. American Congress on Surveying and Mapping, 1990.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.