Long-Term Results of Endoscopic Injection of Botulinum Toxin in Elderly Achalasic Patients with Tortuous Megaesophagus or Epiphrenic Diverticulum - Wehrmann, T.; Kokabpick, H.; Jacobi, V.; Seifert, H.; Lembcke, B.; Caspary, W. F. (Endoscopy, 1999)