1. Johann, Bernoulli, 1 April 1731
2. Newton's Principia for the Common Reader;Chandrasekhar,1995
3. Encyclopedia of Philosophy;Edwards,1972
4. Resisted Inverse-Square Centripetal Force Motion along Newton's Great “Look-Alike,” the Equiangular Spiral;Erlichson;Centaurus,1994
5. The Problem of the Earth's Shape from Newton to Clairaut;Greenberg,1995