RT Journal Article SR Electronic T1 From cross-sectional survey to cohort study JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 428 OP 429 DO 10.1136/oem.2006.027086 VO 66 IS 7 A1 Elsebeth Lynge YR 2009 UL http://oem.bmj.com/content/66/7/428.abstract AB