Pasaworn Ruangrong. (1999) Efficiency concerning service of the river patrol officers : a specific study of the perception of the river tourists in Kanchanaburi province. Mahidol University,:ม.ป.ท.Pasaworn Ruangrong. 1999. Efficiency concerning service of the river patrol officers : a specific study of the perception of the river tourists in Kanchanaburi province. ม.ป.ท.:Mahidol University,;Pasaworn Ruangrong. Efficiency concerning service of the river patrol officers : a specific study of the perception of the river tourists in Kanchanaburi province. ม.ป.ท.:Mahidol University, 1999. Print.