His research includes a study of the Macedonian dialects of Suho and Visoka (published in Makedonski jazik), his habilitation on Balkan conditionals (Cracow, 1964), a monograph on the Arumanian dialect of Krushevo (MANU, 1984), and his last book: The Origins of the Slavs: A Linguist's View (Columbus, 1992).