Sleire, L
Skeie, B S
Netland, I A
Førde, H E
Dodoo, E
Selheim, F
Leiss, L
Heggdal, J I
Pedersen, P-H
Wang, J
Enger, P Ø
Article History
Received: 11 July 2014
Revised: 27 November 2014
Accepted: 16 December 2014
First Online: 23 March 2015
Competing interests
: The authors declare no conflict of interest.