Hagen, Ingerid J.
Jensen, Arne J.
Bolstad, Geir H.
Diserud, Ola H.
Hindar, Kjetil
Lo, HÃ¥vard
Karlsson, Sten
Article History
Received: 13 April 2018
Accepted: 13 December 2018
First Online: 14 January 2019
Competing interests
: The authors declare no competing interests.