Dyfyniad APA

Marble, D. F., Calkins, H. W., & Peuquet, D. J. (1984). Basic readings in geographic information systems. SPAD Systems.

Dyfyniad Arddull Chicago

Marble, Duane F., Hugh W. Calkins, and Donna J. Peuquet. Basic Readings in Geographic Information Systems. Williamsville, N.Y: SPAD Systems, 1984.

Dyfyniad MLA

Marble, Duane F., et al. Basic Readings in Geographic Information Systems. SPAD Systems, 1984.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.