Schlehe, B
Elsässer, M
Bosselmann, S
Axt-Fliedner, R
Sohn, C
Kohl, T
Article History
Received: 10 February 2014
Revised: 23 June 2014
Accepted: 7 July 2014
First Online: 25 November 2014
Competing interests
: The authors declare no conflict of interest.