Lobachevskii Journal of Mathematics
Lobachevskii Journal of Mathematics > 2018 > 39 > 3 > 377-387
Lobachevskii Journal of Mathematics > 2018 > 39 > 3 > 388-397
Lobachevskii Journal of Mathematics > 2018 > 39 > 3 > 377-387
Lobachevskii Journal of Mathematics > 2018 > 39 > 3 > 388-397