Institution: | 1. Department of Mathematics , Kent State University , Kent, OH 44242, USA;2. Departamento de Matematica Aplicada , Facultad de Informatica, Campus Montegancedo s/n , Boadilta del Monte Madrid, 28660, Spain;3. lnst. for Applied Problems of Mechanics and Mathematics, Ukrainian Academy of Sciences , Lviv, 290601, Ukraine3 b, Naukova str |