Ariyaee, K., C. Ben-Ammar, T. Tahtadjian, and A. Kochetov. “The Acoustics of Guttural Fricatives in Three Languages”. Canadian Acoustics, vol. 49, no. 3, Aug. 2021, pp. 28-29, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3906.