Environmental Valuation: An Entrance Fee System for National Parks in Thailand 4 May 20134 May 2013tdriUncategorizednational parks, Adis Israngkura @en, Environmental Valuation @en Year1998-08 AuthorAdis Israngkura Facebook iconfacebookTwitter icontwitterLINE iconlineFacebook iconfacebookTwitter icontwitterLINE iconline