5Costanza R, D'Arge R, Rudolf de Groot, etal. The value of the world's ecosystem services and natural capital.Nature, 1997.
6Tobias D, Mendelsohn R. Valuing ecotourism in a tropical rainforest reserve.Ambio,1991.
7Maille P, Mendelsohn R. Valuing ecotourism in Madagascar. JEnvironMgmt., 1993.
8Loomis J B. Environment valuation techniques in water resource decision making. Journal of Water Resources Planning and Management, 2000.
9Loomis J B. Panel estimators to combine revealed and stated preference dichotomous choice data. Journal of Agricultural and Resources Economics, 1997.
10Mackenzie. A comparison of contingent preferences models. American Journal of Agricultural Economics, 1993.
