1. 1) Allen DS, Graham EA: Intracardiac surgery – a new method. JAMA 1922; 79: 1028–1030
2. 2) Harken DE, Glidden EM: Experiments in intracardiac surgery. II. Intracardiac visualization. J Thorac Surg 1943; 12: 566–572
3. 3) Sakakibara H, Ichikawa T, Hattori J: An intraoperative method for observation of cardiac septal defect using a cardioscope. Operation 1956; 10: 285–290
4. 4) Sakakibara S, Iikawa T, Hattori J, et al: Direct visual operation for aortic stenosis: cardioscopic studies. J Int Coll Surg 1958; 29: 548–562
5. 5) Sugie S, Tanabe T: Observation of the vascular movements by vascular endoscope. Geka 1969; 24: 277–279 (in Japanese)