Sources:
- http://www.preceden.com/timelines/1336-classical-civilizations
- http://www.sunnyvaleisd.com/Page/834
- http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC0QFjAA&url=http%3A%2F%2Fwww.sunnyvaleisd.com%2Fcms%2Flib3%2FTX01001155%2FCentricity%2FDomain%2F191%2FCLASSICAL%2520CIVILIZATIONS%2520-%2520UNIT%25203.pptx&ei=H6CoUaGOFILa8wSJwYDgDA&usg=AFQjCNHELygjxCrjkxgSmi6OXXP--5PGaA&bvm=bv.47244034,d.eWU