Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Philosophiæ Naturalis Principia Mathematica:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

Surviving materials show that Newton (up to some time in 1685) conceived his book as a two-volume work. The first volume was to be titled De motu corporum, Liber primus, with contents that later appeared in extended form as Book 1 of the Principia.[citation needed]