Authors
Marek Balcerzak
Institute of Mathematics, Lodz University of Technology, ĆĂłdĆș, Poland
Tomasz Natkaniec
Institute of Mathematics, Faculty of Mathematics, Physics, and Informatics, University of GdaĆsk, GdaĆsk, Poland
MaĆgorzata Terepeta
Center of Mathematics and Physics, al. Politechniki 11, and Institute of Mathematics, Lodz University of Technology, ĆĂłdĆș, Poland