Vietnam Journal of Mathematics
Vietnam Journal of Mathematics > 2016 > 44 > 1 > 5-28
Vietnam Journal of Mathematics > 2017 > 45 > 4 > 747-761
Vietnam Journal of Mathematics > 2018 > 46 > 2 > 285-291
Vietnam Journal of Mathematics > 2016 > 44 > 1 > 5-28
Vietnam Journal of Mathematics > 2017 > 45 > 4 > 747-761
Vietnam Journal of Mathematics > 2018 > 46 > 2 > 285-291