Authors
P. Potera
Faculty of Mathematics and Natural Sciences University of Rzeszow,, Rzeszow, Poland
I. Virt
Drogobych State Pedagogical University,, Drogobych, Ukraine
G. Wisz
Faculty of Mathematics and Natural Sciences University of Rzeszow,, Rzeszow, Poland
J. Cebulski
Faculty of Mathematics and Natural Sciences University of Rzeszow,, Rzeszow, Poland