Does rare use of assistive devices during patient handling increase the risk of low back pain? A prospective cohort study among female healthcare workers - Andreas Holtermann; Thomas Clausen; Marie Birk Jørgensen; Birgit Aust; Ole Steen Mortensen; Alex Burdorf; Nils Fallentin; Lars L. Andersen (International Archives of Occupational and Environmental Health, 2015)