H. DING, O. JOKISCH, and R. HOFFMANN, “Perception and analysis of Chinese accented German vowels”, Arch. Acoust., vol. 32, no. 1, pp. 89–100, Apr. 2014, Accessed: Apr. 25, 2025. [Online]. Available: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/768