Ferguson, Kitty Pythagoras: His Lives and the Legacy of a Rational Universe Walker Publishing Company, New York, 2008, (page number not available – occurs toward end of Chapter 13, "The Wrap-up of Antiquity").
Truy cập ngày 11 tháng 2 năm 2014.  ^ Ferguson, Kitty Pythagoras: His Lives and the Legacy of a Rational Universe Walker Publishing Company, New York, 2008, (page number not available – occurs toward end of Chapter 13, "The Wrap-up of Antiquity").