Clausen, Per Axel
Spaan, Suzanne
Brouwer, Derk H
Marquart, Hans
le Feber, Maaike
Engel, Roel
Geerts, Lieve
Jensen, Keld Alstrup
Kofoed-Sørensen, Vivi
Hansen, Brian
De Brouwere, Katleen
Article History
Received: 10 December 2014
Accepted: 22 March 2015
First Online: 20 May 2015
Competing interests
: The authors declare no conflict of interest.