Rvachew, S., E. Slawinski, and M. Williams. “Formant Frequencies of Vowels Produced by Infants With and Without Early Onset Otitis Media”. Canadian Acoustics, vol. 24, no. 2, June 1996, pp. 19-28, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/980.