Authors
Paweł Wójcik
Institute of Mathematics, Pedagogical University of Cracow, Podchorazych 2, 30-084, Kraków, Poland
© 2017 Paweł Wójcik, published by University of Silesia in Katowice, Institute of Mathematics
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.