Lewaszkiewicz, Tadeusz. “The Fricative R (ř) and Traces of the Fricative R (ř) in the History of the Polish Language, in Polish Ethnic Dialects and in Polish Spoken in the Southern and Northern Parts of the Polish Pre-War Eastern Borderland [Kresy]”. Gwary Dziś, vol. 15, Dec. 2022, pp. 101-17, doi:10.14746/gd.2022.15.11.