Authors
László Németh
Institute of Mathematics, University of Sopron, Bajcsy Zs. u. 4, 9400, Sopron, Hungary
László Szalay
Department of Mathematics and Informatics, University J. Selye, Hradna ul. 21, 94501, Komarno, Slovakia
Institute of Mathematics, University of Sopron, Bajcsy Zs. u. 4, 9400, Sopron, Hungary