>29</A>
<DD>
D. Matula, G. Marble, and J. Isaacson
<BR><EM>Graph coloring algorithms in Graph Theory and
Computing</EM>.<BR>
Academic Press, pp.104-122, 1972.

<P></P><DT><A NAME="garey79:computers-and-intractability">30</a>
<DD>
M.R. Garey and D.S. Johnson<BR>
<EM>Computers and Intractibility: A Guide to the Theory of
NP-Completeness</EM><BR>
W.H. Freeman, New York, 1979.

<P></P><DT><A NAME="welsch67">31</a>
<DD>D. Welsch and M. B. Powel<BR>
<EM>An upper bound for the chromatic number of a graph and its
a