DJVU PDF Hargreaves, D. 1996, "From interrogation to topicalization: Proto-Tibeto-Burman *la in Kathmandu Newar", in Linguistics of the Tibeto-Burman Area, vol. 19, no. 2, pp. 31-44. cite.

DJVU PDF Benedict, P.K. 1985, "PST interrogative *ga(ng) ~ *ka", in Linguistics of the Tibeto-Burman Area, vol. 8, no. 1, pp. 1-10. cite.

DJVU PDF Clark, M. 1985, "Asking questions in Hmong and other Southeast Asian languages", in Linguistics of the Tibeto-Burman Area, vol. 8, no. 2, pp. 60-67. cite.