Authors
Iwona Bąk
West Pomeranian University of Technology in Szczecin, Faculty of Economics, Department of Applied Mathematics in Economics
Beata Szczecińska
Department of System Analysis and Marketing, Szczecin, Poland
© 2020 Iwona Bąk, Beata Szczecińska, published by University of Physical Education in Warsaw
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.