Vestnik St. Petersburg University, Mathematics
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 1 > 9-17
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 2 > 157-165
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 1 > 9-17
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 2 > 157-165