Kato, Takashi. 2008. Linguistic Survey of Tibeto-Burman languages in Lao P.D.R. Tokyo: Institute for the Study of Languages and Cultures of Asia and Africa (ILCAA).
Further reading
Chazee, Laurent (1995). Atlas des Ethnies et des Sous-Ethnies du Laos (in French). Bangkok. p. 7. OCLC34121376.{{cite book}}: CS1 maint: location missing publisher (link)