GUBRYNOWICZ, Ryszard, Danuta CHOJNACKA-WĄDOŁOWSKA, and Cecylia KONOPKA. 2014. “Assessment of Velum Malfunction in Children through Simultaneous Nasal and Oral Acoustic Signals Measurements”. Archives of Acoustics 32 (1): 165–175. https://acoustics3.ippt.pan.pl/index.php/aa/article/view/775.