1. Castell DO: Achalasia and diffuse esophageal spasm. Arch Intern Med 136:571?579, 1976
2. Cross FS: Pathologic changes in megaesophagus (esophageal dystonia). Surgery 31:647?653, 1952
3. Cassela RR, Brown AL, Sayre GP, Ellis FH: Achalasia of the esophagus: Pathologic and etiologic considerations. Ann Surg 160:474?486, 1964
4. Cassela RR, Ellis FH, Brown AL: Fine structure changes in achalasia of the esophagus. II. Esophageal smooth muscle. Am J Pathol 46:467?475, 1965
5. Misiewicz JJ, Waller SL, Anthony PP, Gummer JWP: Achalasia of the cardia: Pharmacology and histopathology of isolated cardiac sphincteric muscle from patients with and without achalasia. Q J Med 149:17?30, 1969