1. J. Ferguson, Select Mechanical Exercises, 1773.
2. M. Gawrysiak, A fascinating history of planetary gearing (in Polish), 24th Conference on Fundamentals of Machine Design, Białowieża, (2009).
3. K. Hori, Y. Kurita, Improvements in 3K Mechanical Paradox, Planetary Gear Efficiency, Power Transmission and Gearing Conference, (ASME), vol. 88, (1989).
4. K. Hori, I. Hayashi, Improvement of Efficiency of 3K-Type Mechanical Paradox Planetary Drive by Equalising Approach and Recess Contact Ratios. DE - vol. 48, Power Transmission and Gearing Conference (ASME), (1996).
5. A. Golenko, Verification of an Approach and Recess Contact Ratio Equalisation Method (Hori and Hayashi), XLVI International Conference of Machine Design Departments, Sedmihorky, Czech Republic, 2005, p.83 to 86.