
\bigbreak
\noindent{\bigbf References}

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\parindent=50pt

\item{[B]}Babai, L.,
{\sl Spectra of Cayley graphs},
J. Comb. Theory, Ser. B, 27 (1979), 180-189.

\item{[BB]}Blind, G. and Blind, R.,
{\sl The semiregular polytopes},
Comment. Math. Helvetici, 66 (1991), 150-154.

\item{[BCN]}Brouwer, A. E., Cohen, A. M. and Neumaier, A.,
{\sl Distance-regular graphs},
Springer-Verlag, New York, 1989.

\item{[C]}Coxeter, H. S. M.,
{\sl Regular polytopes},
Dover, New York, 1973.

\item{[C1]}Coxeter, H. S. M.,
{\sl Regular and semi-regular polytopes, I},
Math. Zeitschrift, 46 (1940), 380-407.

\item{[C2]}Coxeter, H. S. M.,
{\sl Regular and semi-regular polytopes, II},
Math. Zeitschrift, 188 (1985), 559-591.

\item{[C3]}Coxeter, H. S. M.,
{\sl Regular and semi-regular polytopes, III},
Math. Zeitschrift, 200 (1988), 3-45.

\item{[CCNPW]}Conway, J. H., Curtis, R. T., Norton, S. P.,
Parker, R. A. and Wilson, R. A.,
{\sl Atlas of finite groups},
Clarendon Press, Oxford, 1985.

\item{[CDS]}Cvetkovi\'c, D. M., Doob, M. and Sachs, H.,
{\sl Spectra of graphs},
Academic Press, New York, 1979.

\item{[CS]}Chung, F. R. K. and Sternberg, S.,
{\sl Laplacian and vibrational spectra for homogeneous graphs},
J. Graph Theory, 16 (1992), 605-627.

\item{[Ga]}Gantmacher, F.,
{\sl The theory of matrices},
Chelsea, New York, 1974.

\item{[Go]}Gosset, T.,
{\sl On the regular and semi-regular figures
in space of $n$ dimensions},
Messenger of Math., 29 (1900), 43-48.

\item{[K]}Kepler, J.,
{\sl Harmonice Mundi},
Opera Omnia, vol. 5, Frankfurt, 1864.

\item{[L]}Lov\'asz, L., 
{\sl Spectra of graphs with transitive groups},
Periodica Math. Hungarica, 6 (2) (1975), 191-195.

\item{[MKS]}Magnus, W., Karrass, A. and Solitar, D.,
{\sl Combinatorial group theory},
Interscience, New York, 1966.

\item{[MT]}Mneimn\'e, R. and Testard, F.,
{\sl Introduction \`a la th\'eorie des groupes de Lie classiques},
Hermann, Paris, 1986.

\item{[PS]}Petersdorf, M. and Sachs, H.,
{\sl Spektrum und Automorphismengruppe eines Graphen},
Combinatorial Theory and its Applications
(Colloq. Math. Soc. J. Bolyai, 4),
Amsterdam--London, 1970, 891-907.

\item{[ST]}Saldanha, N. and Tomei, C.,
{\sl Spectra of regular polytopes},
Discrete Comput. Geom., 7 (1992), 403-414.

\item{[Sc]}Schl\"afli, L.,
{\sl Theorie der vielfachen Kontinuit\"at},
Denkschriften der Schweizerischen naturforschenden Gesellschaft,
38 (1901), 1-237.

\item{[Se]}Serre, J. P.,
{\sl Repr\'esentations lin\'eaires des groupes finis},
Hermann, Paris, 1978.

\item{[Su]}Sugiura, M.,
{\sl Unitary representations an harmonic analysis, an introduction},
second edition, North-Holland--Kodansha, Tokyo, 1990.

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Nicolau C. Saldanha, PUC-Rio and IMPA
nicolau@impa.br; http://www.impa.br/$\sim$nicolau/

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Carlos Tomei, PUC-Rio and IMPA
tomei@impa.br

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Departamento de Matem\'atica, PUC-Rio
Rua Marqu\^es de S\~ao Vicente, 225
Rio de Janeiro, RJ 22453-900, Brasil

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IMPA
Estr. Dona Castorina, 110
Rio de Janeiro, RJ 22460-320, Brasil
}
