ŁĘTOWSKI, Tomasz, Lidia ZIMAK, and Halina CIOŁKOSZ-ŁUPINOWA. “Timbre Differences of an Individual Voice in Solo and in Choral Singing”. Archives of Acoustics 13, no. 1-2 (July 10, 2015): 55–65. Accessed April 25, 2025. https://acoustics3.ippt.pan.pl/index.php/aa/article/view/3061.