Funding for this research was provided by:
Narodowym Centrum Nauki (2017/27/B/HS6/00850)
Uniwersytet Jagielloński w Krakowie (221.3110.3.2016)
Accepted: 31 December 2020
First Online: 29 January 2021
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.
: All study procedures were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual students included in the study and from their parents.