Prakorb Phon-ngam. (1999) A morphological study of northern Khmer. Mahidol University,:ม.ป.ท.Prakorb Phon-ngam. 1999. A morphological study of northern Khmer. ม.ป.ท.:Mahidol University,;Prakorb Phon-ngam. A morphological study of northern Khmer. ม.ป.ท.:Mahidol University, 1999. Print.