Theory of Probability and Mathematical Statistics (Theory Probab. Math. Statist. ) (2010), No.~81, 102--113 ISSN: 15477363, 00949000. eISSN: 1547-7363.
Theory of Probability and Mathematical Statistics (Theory Probab. Math. Statist. ) (2009), No.~79, 155--161 ISSN: 15477363, 00949000. eISSN: 1547-7363.