Malmqvist, L
Biering-Sørensen, T
Bartholdy, K
Krassioukov, A
Welling, K-L
Svendsen, J H
Kruse, A
Hansen, B
Biering-Sørensen, F
Article History
Received: 31 May 2014
Revised: 12 August 2014
Accepted: 29 September 2014
First Online: 18 November 2014
Competing interests
: The authors declare no conflict of interest.