Orapin Maneewong. 1987. A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces. Faculty of Graduate Studies, Mahidol University;
Orapin Maneewong. (1987) A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces . Mahidol University/Bangkok.
Orapin Maneewong. A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces. . Bangkok:Mahidol University, 1987.
Orapin Maneewong. (1987) A comparative phonological study of Lao Song in Petchburi and Nakhorn Pathom provinces . Mahidol University/Bangkok.