DJVU Luce, G.H. undated, "Comparative lexicon: OldMon - Palaung - OldKhmer - Bahnar - Stieng - Khasi - Nicobar - Sakai - Khamuk - Lemet - Khmus - So - Boloven - Nyaheun - Huei - Suk - ProuBrao - Ka - Wa/Lawa", in Luce Collection, MS 6574-7, pp. 032a-b. National Library of Australia. cite.

DJVU Luce, G.H. undated, "Comparative lexicon: OldMon - Palaung - OldKhmer - Bahnar - Stieng - Khasi - Nicobar - Sakai - Khamuk - Lemet - Mi - So - Boloven - Nyaheun - Suk - ProuBrao - Huei - Wa/Lawa", in Luce Collection, MS 6574-7, pp. 035a-b. National Library of Australia. cite.

DJVU Luce, G.H. undated, "Comparative lexicon: OldMon - Palaung - OldKhmer - Bahnar - Stieng - Khasi - Nicobar - Sakai - Khmuk - Mi - So - Boloven - Nyaheun - Huei - Suk - ProuBrao - Ka - Wa/Lawa", in Luce Collection, MS 6574-7, pp. 038a-b. National Library of Australia. cite.

DJVU PDF Migliazza, B. 2003, "So stories: a preliminary analysis of texts in a Mon-Khmer language", in The Mon-Khmer Studies Journal, vol. 33, pp. 67-158. cite.

DJVU PDF Miller, C.P. 1996, "Application of typologies for language maintenance and loss to Southeast Asian linguistic minorities: the case of the Bru-So and Kadazan-Dusun language continua", in The Fourth International Symposium on Language and Linguistics, Thailand, pp. 1955-1986. Institute of Language and Culture for Rural Development, Mahidol University. cite.

DJVU PDF Miller, J. and Miller, C. 1996, "Lexical comparison of Katuic Mon-Khmer languages with special focus on So-Bru groups in Northeast Thailand", in The Mon-Khmer Studies Journal, vol. 26, pp. 255-290. cite.