sources

http://www.loc.gov/rr/program/bib/ourdocs/15thamendment.html

http://www.u-s-history.com/pages/h415.html

http://www.usconstitution.net/constamnotes.html

http://www.chacha.com/topic/right-to-vote-15th-amendment

http://experiencinghistory.blogspot.com/2009/02/congress-ratifies-15th-amendment.html