Sierzega, Marek
Kaczor, Marcin
Kolodziejczyk, Piotr
Kulig, Jan
Sanak, Marek
Richter, Piotr
Article History
Received: 27 February 2017
Revised: 31 May 2017
Accepted: 2 June 2017
First Online: 22 June 2017
Competing interests
: The authors declare no conflict of interest.