Mortensen, Jan Helge Seglem
Øyen, Nina
Fomina, Tatiana
Melbye, Mads
Tretli, Steinar
Vollset, Stein Emil
Bjørge, Tone
Article History
Received: 3 June 2015
Revised: 23 November 2015
Accepted: 30 November 2015
First Online: 12 January 2016
Competing interests
: The authors declare no conflict of interest.