Authors
Sylwester Kozak
Warsaw University of Life Sciences, Faculty of Economic Sciences
Łukasz Grzęda
Warsaw University of Life Sciences, Faculty of Economic Sciences
© 2019 Sylwester Kozak, Łukasz Grzęda, published by John Paul II University of Applied Sciences
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.