Siberian Mathematical Journal
Siberian Mathematical Journal > 2017 > 58 > 2 > 255-263
Siberian Mathematical Journal > 2017 > 58 > 5 > 845-849
Siberian Mathematical Journal > 2017 > 58 > 2 > 255-263
Siberian Mathematical Journal > 2017 > 58 > 5 > 845-849