1. Asakura, N., A Study on the Forms drawn by Mathematical Instruments (1), Japanese Society for the Science of Design, Vol 1968, No 8, (1986), DOI:10.11247/jssdj.1968.22. (in Japanese).
2. Bratrongo. and Modesco., Automatically controlled continuously variable transmission, Japanese patent disclosure H1994-6-508418 (1994).
3. Hayashi, H. and Oshima, K., Reducer, Japanese patent disclosure H2019-44953 (2022). (in Japanese).
4. Kamo Seiko Corporation, Nonbacklash Ball educer Serles (2021), p.3. (in Japanese).
5. Kiyosawa, Y. and Kurogi, J., Introduction of Ultra Flat Strain Wave Gearing, Proceedings of Symposium on Motion and Power Transmissions. (2004), pp.76–79. (in Japanese).