RT Journal Article SR Electronic T1 Osteocalcin: a marker of disease activity in ankylosing spondylitis? JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 92 OP 92 DO 10.1136/ard.61.1.92 VO 61 IS 1 A1 A Falkenbach A1 M Herold YR 2002 UL http://ard.bmj.com/content/61/1/92.1.abstract AB