Kenneth Thorsen, Jon Arne Søreide, Jan Terje Kvaløy, Tom Glomsaker, and Kjetil Søreide. [online]. Available : http://www.ncbi.nlm.nih.gov/pmc/articles. (Access date 21 January 2013)
Kenneth Thorsen, Jon Arne Søreide, Jan Terje Kvaløy, Tom Glomsaker, and Kjetil Søreide. [online]. Available : http://www.ncbi.nlm.nih.gov/pmc/articles. (Access date 21 January 2013)