Institution: | (1) Institute of Mathematics, Szczecin University, Szczecin, Poland;(2) Department of Differential Equations and Control, Kharkov State University, Kharkov, Ukraine;(3) Technische Universität Darmstadt, Fachbereich Mathematik, Darmstadt, Germany;(4) Department of Mathematical Analysis, Kharkov State University, Kharkov, Ukraine |