Cambridge Digital Library is a great resource for educators. It, as its name suggests, is an online digital library that holds some of the best available papers. These papers are not published anywhere else and are unique to Cambridge library.
As Anne Jarvis said,” Cambridge University Library contains evidence of some of the greatest ideas and discoveries over two millennia. We want to make our collections accessible to anyone, anywhere in the world with an internet connection and a thirst for knowledge.”
To use this library, you need to head over to its main page and click on ” browse” on the top bar. This will let you navigate through the online library and once you find the notes you want then just click on them and start reading right away. They have some very good papers on Newton theory and his many notebooks to help you understand the principles behind his teachings and the reason that led him to make his great discoveries.