7David S B, Irry S E, Cindy F S. Existence values and normative economics: implication for valuing water resources [J]. Water Resources Research, 1986, 22(11):1509-1518.
8Lan B. Recent developments in the evaluation of non - timber forest products : the extended CBA method [ J ]. Quarterly Journal of Forestry, 1991,85(2 ) : 90-102.
9Kerry V S. Non - market valuation of environmental re- source : an interpretive appraisal [ J ]. Land Economics, 1993, 69 (1) : 1-26.
10Peters C M, Gentry A H, Mendelsohn R O. Valuation of an Amazonian rainforest [ J ]. Nature, 1989, 339 (29) : 655- 656.