3[5]Bronmark C. Internation's epiphytes, macrophytes and freshwater snails, a review[J]. Mol Stud, 1989,55:299～311.
4[7]National Oceanic and Atmospheric Administration. Report of the NOAA panel on contingent valuation[J]. Federal Register,1993, 58(10): 460 ～ 464.
5[8]Lee C K, Han S Y. Estimating the use and preservation values of national park's tourism resources using a contingent valuation method[J]. Tourism Management, 2002, 23:531 ～ 540.
