1. Willis, T.: cited by Hurst.4
2. Ueber Gastroskopie und Oesophagoskopie;von Mikulicz;Mitth. d. Ver. d. Aerzte in Nied. Oesterreich,1882
3. A Case of Dysphagia with Dilatation of the Esophagus;Einhorn;M. Rec.,1888
4. Reports of Royal Society of Medicine;Hurst;Brit. M. J.,1914
5. Liver Tunnel and Cardiospasm;Mosher;Laryngoscope,1922