Althoff, K
Beckers, A
Bell, E
Nortmeyer, M
Thor, T
Sprüssel, A
Lindner, S
De Preter, K
Florin, A
Heukamp, L C
Klein-Hitpass, L
Astrahantseff, K
Kumps, C
Speleman, F
Eggert, A
Westermann, F
Schramm, A
Schulte, J H
Article History
Received: 24 October 2013
Revised: 1 June 2014
Accepted: 8 July 2014
First Online: 1 September 2014
Competing interests
: The authors declare no conflict of interest.