RT Journal Article SR Electronic T1 Journal summary JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 341 OP 342 DO 10.1136/ard.50.6.341 VO 50 IS 6 YR 1991 UL http://ard.bmj.com/content/50/6/341.abstract AB