Kang, E., Y. Liu, A. Purnomo, M. Wang, and B. Gick. “Speaking Versus Smiling: The Labiodentalization of Bilabials in Korean”. Canadian Acoustics, vol. 49, no. 3, Aug. 2021, pp. 36-37, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3932.