Books, Brochures, and Chapters>Book:  Newton , Isaac (1966-01-01), Sir Isaac Newton's Mathematical Principles of Natural Philosophy and His System of the World, Univ of California Press, Retrieved on 2012-08-27

Source Material [books.google.com]

Books, Brochures, and Chapters>Book:  Newton , Isaac (2010-02-01), The Principia: Mathematical Principles of Natural Philosophy, www.snowballpublishing.com, Retrieved on 2011-06-05