Vestnik St. Petersburg University, Mathematics
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 3 > 197-203
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 4 > 361-370
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 3 > 197-203
Vestnik St. Petersburg University: Mathematics > 2016 > 49 > 4 > 361-370