Doke & Mofokeng (1974), ?쪽. sfnp error: 대상 없음: CITEREFDokeMofokeng1974 (help) Doke, Clement Martyn; Mofokeng, S. Machabe (1974), 《Textbook of Southern Sotho Grammar》 3판, Cape Town: Longman Southern Africa, ISBN0-582-61700-6
International Phonetic Association (1999), 13쪽. sfnp error: 대상 없음: CITEREFInternational_Phonetic_Association1999 (help) International Phonetic Association (1999), 《Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet》, Cambridge: Cambridge University Press, ISBN0-521-65236-7
• 완전히 전설 모음인 [ɪ̟]가 있는 언어의 예: 덴마크어와 소토어 (출처: Basbøll (2005:45) harvcoltxt error: 대상 없음: CITEREFBasbøll2005 (help); Doke & Mofokeng (1974:?) harvcoltxt error: 대상 없음: CITEREFDokeMofokeng1974 (help)).
• 완전히 후설 모음인 [ʊ̠]가 있는 언어의 예: 한국어와 소토어 (출처: Lee (1999:121) harvcoltxt error: 대상 없음: CITEREFLee1999 (help); Doke & Mofokeng (1974:?) harvcoltxt error: 대상 없음: CITEREFDokeMofokeng1974 (help)). Basbøll, Hans (2005), 《The Phonology of Danish》, ISBN0-203-97876-5 Doke, Clement Martyn; Mofokeng, S. Machabe (1974), 《Textbook of Southern Sotho Grammar》 3판, Cape Town: Longman Southern Africa, ISBN0-582-61700-6 Lee, Hyun Bok (1999), 〈Korean〉, 《Handbook of the International Phonetic Association》, Cambridge University Press, 120–122쪽, ISBN0-521-63751-1 Doke, Clement Martyn; Mofokeng, S. Machabe (1974), 《Textbook of Southern Sotho Grammar》 3판, Cape Town: Longman Southern Africa, ISBN0-582-61700-6