Brola, W
Sobolewski, P
Szczuchniak, W
Góral, A
Fudala, M
Przybylski, W
Opara, J
Article History
Received: 28 November 2015
Revised: 27 February 2016
Accepted: 29 February 2016
First Online: 30 March 2016
Competing interests
: The authors declare no conflict of interest.