3 Reference

1. https://en.wikipedia.org/wiki/Writing_of_Principia_Mathematica
2. https://blogs.uoregon.edu/scua/2019/02/04/isaac-newtons-work-on-calculus-de-analysi-1711/
3. Book: The Calculus Gallary. by William Dunham. Princeton Press 2005. https://www.britannica.com/biography/James-Gregory
4. A history of Mathematics, by Florian Cajori, 1919.
5. Images, thanks to https://en.wikipedia.org and https://archive.org and https://www.maa.org and https://cosmosmagazine.com