==See also==* African languages* Language families and languages==Footnotes====References==* Casali, Roderic F. (1995) 'On the Reduction of Vowel Systems in Volta–Congo', "African Languages and Cultures", 8, 2, Dec, 109–121.
* Casali, Roderic F. (1995) 'On the Reduction of Vowel Systems in Volta-Congo', "African Languages and Cultures", 8, 2, Dec, 109—121.