Of the large subject of algebraic methods in graph theory, Section 1.9 does
not claim to convey an adequate impression. The standard monograph here is
N.L. Biggs, Algebraic Graph Theory (2nd edn.), Cambridge University Press
1993. Another comprehensive account is given by C.D. Godsil & G.F. Royle,
Algebraic Graph Theory, in preparation. Surveys on the use of algebraic
methods can also be found in the Handbook of Combinatorics (R.L. Graham,
M. Gr¨tschel & L. Lov´sz, eds.), North-Holland 1995.oa