Wiersma, Grace. Yunnan Bai. 2003. wals:6490
ɑo̯ |
The rising diphthongs /i̯ɛ i̯ɑ i̯o i̯ɯ u̯i u̯ɛ u̯ɑ/ and their nasalized equivalents, as well as /i̯ɑo̯/, are here assumed to be CV sequences. /ɑo̯/, the only falling diphthong, is preserved as a single segment.