S. Maikanti, Y. Ngee Thai, J. Martin Burkhardt, Y. Mei Fung, S. Binti Husain, and O. Jacob Oludare, “Mispronunciation and Substitution of Mid-high Front and Back Hausa Vowels by Yorùbá Native Speakers”, REiLA Journal, vol. 3, no. 1, pp. 1-16, Apr. 2021.