Authors: Lennart Balk; Ketil Hylland; Tomas Hansson; Marc H G Berntssen; Jonny Beyer; Grete Jonsson; Alf Melbye; Merete Grung; Bente E Torstensen; Jan Fredrik Børseth; Halldora Skarphedinsdottir; Jarle Klungsøyr Journal: PLoS One Date: 2011-05-23 Impact factor: 3.240