Orhon , Elif Şahin, and Tülün Malkoç. “The Effects of Yawn-Sigh, Lip Trill and Tongue Relaxation Exercises on Frequency and Amplitude Perturbation of Voice in Vocal Training”. Cypriot Journal of Educational Sciences 17, no. 1 (January 31, 2022): 01–17. Accessed November 22, 2024. https://un-pub.eu/ojs/index.php/cjes/article/view/6649.