RT Journal Article SR Electronic T1 Ascertaining computer use in studies of musculoskeletal outcomes among computer workers: differences between self-report and computer registration software JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 465 OP 466 DO 10.1136/oemed-2011-100116 VO 68 IS 7 A1 Fred Gerr A1 Nate Fethke YR 2011 UL http://oem.bmj.com/content/68/7/465.abstract AB