http://book.klll.cc/ebooks/subject/8645.opds?sort_order=title 2025-11-16T02:12:40Z Books about Celestial mechanics -- Early works to 1800 Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-11-16T02:12:40Z https://book.klll.cc/ebooks/76404.opds Newton's Principia : The mathematical principles of natural philosophy Isaac Newton 2025-11-16T02:12:40Z https://book.klll.cc/ebooks/28233.opds Philosophiae Naturalis Principia Mathematica (Latin) Isaac Newton