Frege's Logic, Theorem, and Foundations for Arithmetic  
   Stanford Encyclopedia article on Frege's work on the foundations of mathematics.
   http://plato.stanford.edu/entries/frege-logic/

Frege: Two Theses, Two Senses  
   Article by Carlo Penco discusses a vacillation by Frege in his account of the relation between thoughts and sentences. Penco discusses the attempts to resolve this uncertainty by Currie, Dummett and others before advancing his own account.
   http://www.dif.unige.it/epi/hp/penco/pub/2th.htm

A Slice of Philosophy: Gottlob Frege (1848-1925)  
   A slice of Frege's life and works. Listing of all his works and suggestions to secondary literature.
   http://www.findlink.dk/frege/frege.htm

Frege  
   Article in Björn's Guide To Philosophy.
   http://www.student.liu.se/~bjoch509/philosophers/fre.html

Gottlob Frege  
   Biography from Wikipedia.
   http://en.wikipedia.org/wiki/Frege

On Sense and Reference  
   English translation of Gottlob Frege's 1892 "Über Sinn und Bedeutung," by Max Black.
   http://wikisource.org/wiki/On_Sense_and_Reference