%0 Journal Article %A A Micheli %T Proceedings: Frequency of the atypical gene E1-a of serum cholinesterase among patients with ankylosing spondylitis. %D 1975 %R 10.1136/ard.34.2.198-c %J Annals of the Rheumatic Diseases %P 198 %V 34 %N 2 %U https://ard.bmj.com/content/annrheumdis/34/2/198.3.full.pdf