History 6-4

This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”
http://www-history.mcs.st-and.ac.uk/~history/

This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu

Descartes:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Descartes.html

Al-Khwarizmi:See the whole entry

History 6-1

This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”
http://www-history.mcs.st-and.ac.uk/~history/

This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu/

Al-Khwarizmi:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Al-Khwarizmi.html

Abel:See the whole entry