DJVU PDF Thongkum, T.L. 1992, "The raising and lowering of pitch caused by a voicing distinction in sonorants (nasals and approximants): an epidemic disease in SEA languages", in The Third International Symposium on Language and Linguistics, Bangkok, Thailand, pp. 1079-1088. Chulalongkorn University. cite.
DJVU PDF Theraphan L-Thongkum. 1988, "Another look at the register distinction in Mon", in The International Symposium on Language and Linguistics, ed. C. Bamroongraks et al., Bangkok, Thailand, pp. 22-51. Thammasat University. cite.