@article{PES, author = {Jan Polcyn}, title = { Zestaw informacji o numerze 4 (2017)}, journal = {Progress in Economic Sciences}, number = {4}, year = {2017}, keywords = {}, abstract = {}, issn = {2391-5951}, url = {http://pes.pwsz.pila.pl/index.php/PES/article/view/134} }