Dyfyniad APA

(1991). Geographical information systems: Principles and applications. Harlow, Essex, England: Longman Scientific & Technical.

Dyfyniad Arddull Chicago

Geographical Information Systems: Principles and Applications. Harlow, Essex, England: Longman Scientific & Technical, 1991.

Dyfyniad MLA

Geographical Information Systems: Principles and Applications. Harlow, Essex, England: Longman Scientific & Technical, 1991.

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