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\providecommand{\MR}{\relax\ifhmode\unskip\space\fi MR }
% \MRhref is called by the amsart/book/proc definition of \MR.
\providecommand{\MRhref}[2]{%
  \href{http://www.ams.org/mathscinet-getitem?mr=#1}{#2}
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\providecommand{\href}[2]{#2}
\begin{thebibliography}{BGGS92}

\bibitem[AS68]{Atiyah:1968}
M.F. Atiyah and I.M. Singer, \emph{The index of elliptic operators}, Ann. of
  Math. \textbf{87} (1968), 546--604.

\bibitem[Bar99]{Barnes:1899}
E.W. Barnes, \emph{The theory of the {G}-function}, Quart. J. Math. \textbf{31}
  (1899), 264--314.

\bibitem[Bau81]{Baum:1981}
H.~Baum, \emph{Spin-{S}trukturen und {D}irac-{O}peratoren \"uber
  {P}seudo-{R}iemannschen {M}annigfaltigkeiten}, Teubner-Verlag Leipzig, 1981.

\bibitem[BG80]{Brin:1980}
M.~Brin and M.~Gromov, \emph{On the ergodicity of frame flows}, Invent. Math.
  \textbf{60} (1980), 1--7.

\bibitem[BGGS92]{Bogomolny:1992}
E.~Bogomolny, B.~Georgeot, M.~J. Giannoni, and C.~Scmmit, \emph{{Chaotic
  billiards generated by arithmetic groups}}, Phys. Rev. Lett. \textbf{69}
  (1992), 1477--1480.

\bibitem[BGS84]{Bohigas:1984}
O.~Bohigas, M.~J. Giannoni, and C.~Schmit, \emph{{Characterization of chaotic
  quantum spectra and universality of level fluctuation laws}}, {Phys. Rev.
  Lett.} \textbf{52} (1984), 1--4.

\bibitem[BH03]{Bolte:2003}
J.~Bolte and J.~M. Harrison, \emph{Spectral statistics for the {D}irac operator
  on graphs}, J. Phys. A: Math. Gen. \textbf{36} (2003), 2747--2769.

\bibitem[BK99]{Bolte:1999}
J.~Bolte and S.~Keppeler, \emph{{A semiclassical approach to the {D}irac
  equation}}, {Ann. Phys. (NY)} \textbf{274} (1999), 125--162.

\bibitem[BO95]{Bunke:1995}
U.~Bunke and M.~Olbrich, \emph{Selberg zeta and theta functions}, Akademie
  Verlag, 1995.

\bibitem[BSS92]{Bolte:1992}
J.~Bolte, G.~Steil, and F.~Steiner, \emph{{Arithmetical chaos and violation of
  universality in energy level statistics}}, Phys. Rev. Lett. \textbf{69}
  (1992), 2188--2191.

\bibitem[CGO93]{Comtet:1993}
A.~Comtet, B.~Georgeot, and S.~Ouvry, \emph{{Trace formula for {R}iemann
  surfaces with magnetic field}}, Phys. Rev. Lett. \textbf{71} (1993),
  3786--3789.

\bibitem[Erd53]{Erdelyi:1953}
A.~Erd\'elyi, \emph{Higher transcendental functions}, vol.~1, Mc Graw-Hill,
  1953.

\bibitem[Fri97]{Friedrich:1997}
T.~Friedrich, \emph{Dirac-{O}peratoren in der {R}iemannschen {G}eometrie},
  Vieweg Verlag Braunschweig, 1997.

\bibitem[GR65]{Gradshteyn:1965}
I.S. Gradshteyn and I.M. Ryzhik, \emph{Table of integrals, series and
  products}, 4th ed., Academic Press, 1965.

\bibitem[Gun56]{Gunning:1956}
R.C. Gunning, \emph{The structure of factors of automorphy}, Amer. J. Math.
  \textbf{78} (1956), 357--382.

\bibitem[Gun76]{Gunning:1976}
\bysame, \emph{Riemann surfaces and generalized theta functions},
  Springer-Verlag, 1976.

\bibitem[Hej76]{Hejhal:1976}
D.A. Hejhal, \emph{The {S}elberg trace formula for {$\psl$}}, vol.~1,
  Springer-Verlag, 1976.

\bibitem[Hej83]{Hejhal:1983}
\bysame, \emph{The {S}elberg trace formula for $\psl$}, vol.~2,
  Springer-Verlag, 1983.

\bibitem[Hit74]{Hitchin:1974}
N.~Hitchin, \emph{Harmonic spinors}, Adv. in {M}athematics \textbf{14} (1974),
  1--55.

\bibitem[JS06]{Jakobson:2006}
D.~Jakobson and A.~Strohmaier, \emph{High energy limits of {L}aplace-type and
  {D}irac-type eigenfunctions and frame flows}, preprint, 2006.

\bibitem[Kra30]{Kramers:1930}
H.~Kramers, \emph{{Th\'eorie g\'en\'erale de la rotation paramagn\'etique dans
  le cristaux}}, Proc. Acad. Amst. \textbf{33} (1930), 959--972.

\bibitem[Maa53]{Maass:1953}
H.~Maa\ss, \emph{Die {D}ifferentialgleichungen in der {T}heorie der
  elliptischen {M}odulfunktionen}, Math. Ann. \textbf{125} (1953), 235--263.

\bibitem[MOS66]{Magnus:1966}
W.~Magnus, F.~Oberhettinger, and R.P. Soni, \emph{Formulas and theorems for the
  special functions of mathematical physics}, 3rd ed., Springer-Verlag, 1966.

\bibitem[Pnu94]{Pnueli:1994}
A.~Pnueli, \emph{Spinors and scalars on {R}iemann surfaces}, J. Phys. A: Math.
  Gen. \textbf{27} (1994), 1345--1352.

\bibitem[Roe66]{Roelcke:1966}
W.~Roelcke, \emph{Das {E}igenwertproblem der automorphen {F}ormen in der
  hyperbolischen {E}bene {I}}, Math. Ann. \textbf{167} (1966), 292--337.

\bibitem[Roe67]{Roelcke:1967}
\bysame, \emph{Das {E}igenwertproblem der automorphen {F}ormen in der
  hyperbolischen {E}bene {II}}, Math. Ann. \textbf{168} (1967), 261--324.

\bibitem[Sar87]{Sarnak:1987}
P.~Sarnak, \emph{Determinants of {L}aplacians}, Commun. Math. Phys.
  \textbf{110} (1987), 113--120.

\bibitem[Sel56]{Selberg:1956}
A.~Selberg, \emph{Harmonic analysis and discontinuous groups in weakly
  symmetric {R}iemannian spaces with applications to {D}irichlet series}, J.
  Indian Math. Soc. \textbf{20} (1956), 47--87.

\bibitem[Ste87]{Steiner:1987}
F.~Steiner, \emph{{On {S}elberg's zeta function for {R}iemann surfaces}}, Phys.
  Lett. \textbf{188B} (1987), 447--454.

\bibitem[Tha92]{Thaller:1992}
B.~Thaller, \emph{The {D}irac {E}quation}, {Texts and Monographs in Physics},
  Springer-Verlag, Berlin, 1992.

\bibitem[Zir96]{Zirnbauer:1996}
M.~Zirnbauer, \emph{{R}iemannian symmetric superspaces and their origin in
  random matrix theory}, J. Math. Phys. \textbf{37} (1996), 4986--5018.

\end{thebibliography}