International Mathematical Forum. Journal for Theory and Applications (Int. Math. Forum) (20130101), 8, no.~9-12, 527-536. ISSN: 1312-7594 (print).eISSN: 1314-7536.
International Mathematical Forum. Journal for Theory and Applications (Int. Math. Forum) (20130101), 8, no.~9-12, 567-572. ISSN: 1312-7594 (print).eISSN: 1314-7536.