Ulrich, Werner http://orcid.org/0000-0002-8715-6619
Sewerniak, Piotr
Puchałka, Radosław http://orcid.org/0000-0002-4764-0705
Piwczyński, Marcin
Article History
Received: 9 December 2016
Accepted: 15 February 2017
First Online: 21 March 2017
Competing Interests
: The authors declare that they have no competing interests.