Sila และ Phung. (1993) Roles of forest extensionists in community forestry : a case study of Khon Kaen regional and provincial forest extension offices, Thailand. Khon Kaen University,:ม.ป.ท.Sila และ Phung. 1993. Roles of forest extensionists in community forestry : a case study of Khon Kaen regional and provincial forest extension offices, Thailand. ม.ป.ท.:Khon Kaen University,;Sila และ Phung. Roles of forest extensionists in community forestry : a case study of Khon Kaen regional and provincial forest extension offices, Thailand. ม.ป.ท.:Khon Kaen University, 1993. Print.