Raknes, Guttorm http://orcid.org/0000-0002-3376-6761
Småbrekke, Lars http://orcid.org/0000-0001-6475-3368
Article History
Received: 20 May 2019
Accepted: 3 October 2019
First Online: 21 October 2019
Competing interests
: The authors declare no competing interests.