G. Ahumada, Fonctions periodiques et formule des traces de Selberg sur les
arbres, C. R. Acad. Sci. Paris, 305 (1987), 709-712.
N. Allen, On the spectra of certain graphs arising from finite fields, Finite
Fields Applies., 4 (1998), 393-440.
J. Angel, Finite upper half planes over finite fields, Finite Fields Applies., 2
(1996), 62-86.
J. Angel, B. Shook, A. Terras, C. Trimble, Graph spectra for finite upper half
planes over rings, Linear Algebra and its Applications, 226-228 (1995), 423-
457.
C. Ballantine, Ramanujan type buildings, Canad. J. Math., 52 (2000), 1121-
1148.
E. Bannai, Character tables of commutative association schemes, in Finite
Geometries, Buildings, and Related Topics, (W. M. Kantor, et al, Eds.),
Clarendon Press, Oxford, 1990 , pp. 105-128.
E. Bannai, 0. Shimabukuro, and H. Tanaka, Finite euclidean graphs and Ra-
manujan graphs, preprint.
H. Bass, The Ihara-Selberg zeta function of a tree lattice, Internatl. J. Math.,
3 (1992), 717-797.
C. Beguin, A. Valette, and A. Zuk, On the spectrum of a random walk on the
discrete Heisenberg group and the norm of Harper's operator, J. of Geometry
and Physics, 21 (1997), 337-356.
N. Biggs, Algebraic Graph Theory, Cambridge U. Press, Cambridge, 1974.
Bohigas and M.-J. Giannoni, Chaotic motion and random matrix theories,
Lecture Notes in Physics, 209 , Springer-Verlag, Berlin, 1984, pp. 1-99.
Bohigas, R.U. Haq, and A. Pandey, Fluctuation properties of nuclear energy
levels and widths: comparison of theory with experiment, in K.H. Bockhoff
(Ed.), Nuclear Data for Science and Technology, Reidel, Dordrecht, 1983, pp.
809-813.
B. Bollobas, Modern Graph Theory, Springer-Verlag, N.Y., 1998.
A. Borel and G. D. Mostow, Algebraic Groups and Discontinuous Subgroups,
Proc. Symp. Pure Math., IX, Amer. Math. Soc., Providence, 1966.
R. Brooks, The spectral geometry of k-regular graphs, J. d'Analyse, 57 (1991),
120-151.
371
