Andersson, Y
Engebraaten, O
Juell, S
Aamdal, S
Brunsvig, P
Fodstad, Ø
Dueland, S
Article History
Received: 19 March 2015
Revised: 15 September 2015
Accepted: 6 October 2015
First Online: 10 November 2015
Competing interests
: The authors declare no conflict of interest.