Gudra, T., Opieliński, K. and Sobczak, T. (2014) “Ultrasonic examination of the tongue shape changes in the process of articulation of vowels”, Archives of Acoustics, 31(4(S), pp. 9–16. Available at: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/1316 (Accessed: 26 April 2025).