Citation: M. Hakala et al., HIGH PREVALENCE OF RHEUMATOID-FACTOR IN COMMUNITY-BASED SERIES OF PATIENTS WITH RHEUMATOID-ARTHRITIS MEETING THE NEW (1987) ARA CRITERIA - RF-NEGATIVE NONEROSIVE RHEUMATOID-ARTHRITIS IS VERY RARE, Scandinavian journal of rheumatology, 27(5), 1998, pp. 368-372