RT Journal Article SR Electronic T1 Anne Cockroft and Paul Griffiths reply JF British Journal of Industrial Medicine JO Br J Ind Med FD BMJ Publishing Group Ltd SP 645 OP 646 DO 10.1136/oem.47.9.645-a VO 47 IS 9 YR 1990 UL http://oem.bmj.com/content/47/9/645.2.abstract AB