DJVU PDF Alves, M. 2001, "Distributional properties of causative verbs in some Mon-Khmer languages", in The Mon-Khmer Studies Journal, vol. 31, pp. 107-120. cite.

DJVU PDF Costello, N. 2001, "Aspect and tense in Katu of the Lao PDR", in The Mon-Khmer Studies Journal, vol. 31, pp. 121-125. cite.