Harmonies of the World, by Johannes Kepler, tr. Charles Glenn Wallis [1939], at sacred-texts.com
Scanned at sacred-texts.com, April 2007. Proofed and formatted by John Bruno Hare. This text is in the public domain in the United States because its copyright was not renewed in a timely fashion as required at the time by law. These files may be used for any non-commercial purpose, provided this notice of attribution is left intact in all copies.