Vowels without stagnation in communional language

Bogoroditsky, Vasily Alekseevich (1857-1941).Vowels without emphasis in the communional language: DISS.The degree of Master of Comparative Language Science V. Bogoroditsky.- Kazan: Type.Imp.University, 1884. - [4], 144, [1] p., 1 l.Table.;23. -.Electronic Source: PB