Durie & Hajek (1994:?) Durie, M.; Hajek, J. (1994), A revised standard phonemic orthography for Australian English vowels, Australian Journal of Linguistics, 14 (1): 93–107, doi:10.1080/07268609408599503
Iivonen & Harnud (2005:62, 66–67) Iivonen, Antti; Harnud, Huhe (2005), Acoustical comparison of the monophthong systems in Finnish, Mongolian and Udmurt, Journal of the International Phonetic Association, 35 (1): 59–71, doi:10.1017/S002510030500191X