1. Overholt BF. Description and experiences with flexible fibersigmoidoscopy. In: Proc Sixth National Cancer Conference (1968). Philadelphia: JB Lippincott, 1970:443–6.
2. Overholt BF. Clinical experience with the fibersigmoidoscope. Gastrointest Endosc 1968;15:27.
3. Overholt BF. Flexible fiberoptic sigmoidoscopes. Cancer 1969;19:81–4.
4. Niwa H. Clinical study of colono-fiberscope. Gastrointest Endosc (Tokyo) 1969;11:173–5.
5. Yamagata S. Clinical experience of fibercolonoscope type VI. Gastrointest Endosc (Tokyo) 1969;11:219.