TY - JOUR T1 - CORRECTION JF - British Journal of Industrial Medicine JO - Br J Ind Med SP - 164 LP - 164 DO - 10.1136/oem.25.2.164 VL - 25 IS - 2 A2 - , Y1 - 1968/04/01 UR - http://oem.bmj.com/content/25/2/164.abstract N2 - 300 Multiple ChoicesThis is a pdf-only article and there is no markup to show you.full-text.pdf ER -