Freeman, A. M. (2003). The measurement of environmental and resource values: Theory and methods (2nd ed.). Resources for the Future.
Dyfyniad Arddull ChicagoFreeman, A. Myrick. The Measurement of Environmental and Resource Values: Theory and Methods. 2nd ed. Washington, DC: Resources for the Future, 2003.
Dyfyniad MLAFreeman, A. Myrick. The Measurement of Environmental and Resource Values: Theory and Methods. 2nd ed. Resources for the Future, 2003.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.