Bibliografi Vokal_tak_bundar_hampir_depan_hampir_sempit

  • Barbosa, Plínio A.; Albano, Eleonora C. (2004), "Brazilian Portuguese", Journal of the International Phonetic Association, 34 (2): 227–232 
  • 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 
  • Jones, Daniel & Ward Dennis (1969), The Phonetics of Russian, Cambridge University Press