A decision analysis of the optimal initial approach to achalasia: laparoscopic Heller myotomy with partial fundoplication, thoracoscopic Heller myotomy, pneumatic dilatation, or botulinum toxin injection. - Urbach,D.R.; Hansen,P.D.; Khajanchee,Y.S.; Swanstrom,L.L. (J Gastrointest Surg, 2001)