1. Gergely Bencsik, Involute gears explained, July 2022, \url{https://www.youtube.com/watch?v=nrsCoQN6V4M}.
2. Bálint Laczik, Involute profile of non-circular gears, Available from \url{http://manuals.chudov.com/Non-Circular-Gears.pdf}.
3. Jinesh Machchhar, Henry Segerman, and Gershon Elber, Conjugate shape simplification via precise algebraic planar sweeps toward gear design, Computers & Graphics 90 (2020), 1–10.
4. Elisabetta A. Matsumoto and Henry Segerman, Five axis racks, September 2018, \url{https://www.youtube.com/watch?v=dkguSyeQXjc}.
5. Elisabetta A. Matsumoto and Henry Segerman, Geared jitterbug, October 2018, \url{https://www.youtube.com/watch?v=kwERR5flAOU}.