References:
J. Silvestre, "Notes sur les châu lao du Tonkin", Excursions et Reconnaissances, (Saigon), XI, No. 26, III-IV, March-April 1886, p.169-172. (Information about the Tai language.)
See also: http://www.omniglot.com/writing/taidam.htm (Black Tai language info)