Digraphs: Theory, Algorithms and Applications
- A comprehensive source of results, notions and open problems on directed graphs. Site offers the entire book for download as well as information on solved conjectures from the book.
- http://www.cs.rhul.ac.uk/books/dbook/

Algebraic Graph Theory
- Home page for graduate level textbook "Algebraic Graph Theory" by Chris Godsil and Gordon Royle, published by Springer-Verlag, 2001.
- http://cuscus.math.uwaterloo.ca/agt/

Graph Theory 1736-1936
- Two centuries of Graph Theory, by Norman L. Biggs, E. Keith Lloyd, and Robin J. Wilson.
- http://www.oup-usa.org/toc/tc_0198539169.html

Graph Theory
- By Reinhard Diestel. Sites offers author and book information as well as a downloadable PDF version of the book.
- http://www.math.uni-hamburg.de/home/diestel/books/graph.theory/

Douglas West's Books
- Home page of D. West with description of his books: Introduction to Graph Theory, Mathematical Thinking: Problem-Solving and Proofs, Combinatorics: A Core Course, The Art of Combinatorics.
- http://www.math.uiuc.edu/~west/