@article {BHI00a, title = {On a well solvable class of the {PNS} problem}, journal = {Novi Sad Journal of Mathematics}, volume = {30}, number = {3}, year = {2000}, pages = {21-30}, author = {Z. Bl{\'a}zsik and Cs. Holl{\'o} and B. Imreh and Cs. Imreh and Z. Kov{\'a}cs} }