Marble, D. F., Calkins, H. W., & Peuquet, D. J. (1984). Basic readings in geographic information systems. SPAD Systems.
Lua i Stíl Chicago (17ú heag.)Marble, Duane F., Hugh W. Calkins, agus Donna J. Peuquet. Basic Readings in Geographic Information Systems. Williamsville, N.Y: SPAD Systems, 1984.
Lua MLA (9ú heag.)Marble, Duane F., et al. Basic Readings in Geographic Information Systems. SPAD Systems, 1984.
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