Haugen, Linda Hofstad
Skjeldal, Frode Miltzow
Bergeland, Trygve
Bakke, Oddmund http://orcid.org/0000-0003-4843-7626
Article History
Received: 31 March 2017
Accepted: 25 October 2017
First Online: 21 December 2017
Competing Interests
: The authors declare that they have no competing interests.