Orapin Maneewong. (1987) A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces. Mahidol University,:ม.ป.ท.Orapin Maneewong. 1987. A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces. ม.ป.ท.:Mahidol University,;Orapin Maneewong. A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces. ม.ป.ท.:Mahidol University, 1987. Print.