Grajda, A http://orcid.org/0000-0003-3289-2878
Kułaga, Z
Gurzkowska, B
Wojtyło, M
Góźdź, M
Litwin, M
Article History
Received: 11 July 2016
Revised: 15 November 2016
Accepted: 18 November 2016
First Online: 29 December 2016
Competing interests
: The authors declare no conflict of interest.