Panic, Andrej
Ketteler, Julia
Reis, Henning
Sak, Ali
Herskind, Carsten
Maier, Patrick
RĂ¼bben, Herbert
Jendrossek, Verena
Klein, Diana
Article History
Received: 13 September 2016
Accepted: 15 December 2016
First Online: 23 January 2017
Competing interests
: The authors declare no competing financial interests.