Bentsen, M H
Satrell, E
Reigstad, H
Johnsen, S L
Vollsæter, M
Røksund, O D
Greve, G
Berg, A
Markestad, T
Halvorsen, T
Article History
Received: 8 November 2016
Revised: 20 April 2017
Accepted: 27 April 2017
First Online: 29 June 2017
Competing interests
: The authors declare no conflict of interest.