http://book.klll.cc/ebooks/author/58433.opds 2025-11-17T04:14:42Z Books by Chittenden, N. W. Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-11-17T04:14:42Z https://book.klll.cc/ebooks/76404.opds Newton's Principia : The mathematical principles of natural philosophy Isaac Newton