'The Five Ways' Summa Theologica First Part Question 2
http://www.newadvent.org/summa/100203.htm
 

Two biographies

• Jacques Maritain Center : Readings http://www.nd.edu/Departments/Maritain/etext/stthomas.htm
• The Catholic Encyclopedia, Volume XIV http://www.newadvent.org/cathen/14663b.htm

Two principal works of Aquinas

• Sumnma Theologiae  http://www.newadvent.org/summa/
• Summa Contra Gentiles  http://www.nd.edu/Departments/Maritain/etext/gc.htm

A list of web sites

from Philosophy for Everyone
http://www.geocities.com/Athens/Delphi/2795/thomas_aquinas.htm