1. Removal of razor blades from the stomach with fibreoptic endoscope;Witzel, L.; Scheurer, U.; Muhlemann, A.; Halter, F.;Br Med J,1974
2. Fibreendoscopic removal of long foreign bodies from the stomach using a colon stiffening tube as a protective sheath;Martin, W.C.; Jones, S.A.; Nagai, N.; EC, Jr, Texter;Am J Gastroenterol,1979
3. Gastrointest Endosc 1979; 25: 47.
4. An over-tube (sleeve) concept at upper GI endoscopy;Cotton, P.B.;(Abstract.) Gut,1981
5. Endoscopic overtubes;Szpak, M.W.;(Abstract.) Gastrointest Endosc,1981