IGRAS, Magdalena, KACPRZAK, Stanisław, MĄSIOR, Mariusz and ZIÓŁKO, Mariusz. The acoustic diversity in the phoneme inventories of the world’s languages. Theoria et Historia Scientiarum. Online. 30 January 2015. Vol. 11, pp. 117-128. [Accessed 18 July 2024]. DOI 10.12775/ths-2014-007.