RT Journal Article SR Electronic T1 The Art of Scientific Investigation JF British Journal of Industrial Medicine JO Br J Ind Med FD BMJ Publishing Group Ltd SP 164 OP 164 DO 10.1136/oem.11.2.164 VO 11 IS 2 A1 Fletcher, C. M. YR 1954 UL http://oem.bmj.com/content/11/2/164.abstract AB