U at Ethnologue (18th ed., 2015) (subscription required)
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Svantesson (1988) Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.
Svantesson 1988, p. 69 Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.
Svantesson 1988, p. 70 Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.
Svantesson (1988) Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.
Svantesson 1988, p. 69 Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.
Svantesson 1988, p. 70 Svantesson, Jan-Olof (1988). "U"(PDF). Linguistics of the Tibeto-Burman Area. 11 (1): 64–133. Archived(PDF) from the original on 2014-02-23. Retrieved 2012-06-02.