He was imprisoned that same year, but managed to escape prior to the liberation of Kraków by the Red Army.
He served as a professor at the John Paul II Catholic University of Lublin during 1952–1961,[2] and also at the Slavic Institute of the Polish Academy of Learning (1955–1961).
Afterward he emigrated to the United States where he taught Slavic languages at the University of Chicago from 1962 until his retirement in 1993 as professor emeritus.
His research includes a study of the Macedonian dialects of Suho and Visoka (published in Makedonski jazik), his habilitation on Balkan conditionals (Cracow, 1964),[3] a monograph on the Arumanian dialect of Krushevo (1984),[4] and his last book: The Origins of the Slavs: A Linguist's View (Columbus, 1992).
He also co-edited a dictionary of linguistic terminology (Warsaw, 1968) and was the author of more than 70 articles and reviews.