WSZOŁEK, Wiesław, and Maciej KŁACZYŃSKI. “Estimation Of The Vocal Folds Vibration Fundamental Frequency by Higer Order Spectrum”. Archives of Acoustics 33, no. 4(S) (December 1, 2008): 183–188. Accessed January 18, 2026. https://acoustics.ippt.gov.pl/index.php/aa/article/view/856.