Extensive lessons on graph theory by Christopher Mawata, University of Tennessee at Chattanooga, are available at http://www.utc.edu/~cpmawata/petersen/. Professor Mawata also wrote a software package called Petersen that is available for downloading at http://www.utc.edu/~cpmawata/petersen/download.htm. Documentation about the package is at http://www.utc.edu/~cpmawata/petersen/intro.htm. Another introductory site is http://www.c3.lanl.gov/mega-math/workbk/graph/grbkgd.html. My program graph_ge.c generates random graphs of various types.

The Oracle of Bacon at http://www.cs.virginia.edu/oracle/bacon_info.html gives an upper bound (which is usually exact) on the Bacon number of almost any actor. The site can also give an upper bound on the length of a shortest path from almost any actor to any other.

See http://www.keypress.com/sketchpad/java_gsp/hypercube.html.

A biography of Erdos is at http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Erdos.html. The Erdos Number Project at http://www.acs.oakland.edu/~grossman/erdoshp.html is maintained by Jerrold Grossman, Oakland University.

There is no longer a link for this algorithm.

A discussion of the Koenigsberg Bridge Problem is at http://mathforum.org/isaac/problems/bridges1.html. A biography of Euler is at http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Euler.html.