.Lo, C. P., & .Yeung, A. K. W. (2007). Concepts and techniques of geographic information systems (2nd ed.). Pearson Prentice Hall.
Dyfyniad Arddull Chicago.Lo, C. P., and Albert K. W. .Yeung. Concepts and Techniques of Geographic Information Systems. 2nd ed. .Upper Saddle River, NJ: Pearson Prentice Hall, 2007.
Dyfyniad MLA.Lo, C. P., and Albert K. W. .Yeung. Concepts and Techniques of Geographic Information Systems. 2nd ed. Pearson Prentice Hall, 2007.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.