I.V. Boykov - Dr.Sc. (Phys.-Math.), Professor, Head of Chair «Higher and Applied Mathematics», Penza State University. E-mail: boikov@pnzgu.ru
V.A. Roudnev - Ph.D. (Phys.-Math.), Research Assistant Professor, Department of Physics and Astronomy, University of Kentucky. E-mail: roudnev@pa.uky.ed
A.I. Boykova - Ph.D. (Phys.-Math.), Associate Professor, Associate Professor of Chair «Higher and Applied Mathematics», Penza State University. E-mail: allaboikova@sura.ru