RT Journal Article SR Electronic T1 Antecedents of achalasia. JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 861 OP 862 DO 10.1136/gut.35.6.861 VO 35 IS 6 A1 Atkinson, M YR 1994 UL http://gut.bmj.com/content/35/6/861.abstract AB