\begin{thebibliography}{10}

\bibitem{DimMue}
A.\ Dimakis and F.\ M\"uller-Hoissen.
\newblock Discrete differential calculus, graphs, topologies, and gauge theory.
\newblock {\em J.\ Math.\ Phys.}, 35:6703--6735, 1994.

\bibitem{DoySne}
P.G.\ Doyle and J.L.\ Snell.
\newblock {\em Random walks and electric circuits}.
\newblock The Mathematical Association of America, Washnigton DC, 1988.

\bibitem{FerFroSok}
R.\ Fern\'andez, J.\ Fr\"ohlich, and A.\ Sokal.
\newblock {\em Random walks, critical phenomena and triviality in quantum field
  theory}.
\newblock Springer-Verlag, Berlin, 1992.

\bibitem{Guillotin}
N.\ Guillotin.
\newblock Marche aléatoire dynamique dans une scène aléatoire. {P}roblèmes liés
  à l'inhomogénéité spatiale de certaines chaînes de {M}arkov; {PhD} thesis:
  {U}niversit\'e de {R}ennes 1, 1997.

\bibitem{KesSpi}
H.\ Kesten and F.\ Spitzer.
\newblock A limit theorem related to a new class of self-similar process.
\newblock {\em Z.\ Wahrscheinlichkeitstheorie verw.\ Gebiete}, 50:5--25, 1979.

\bibitem{MenPet-wedge}
M.\ Menshikov and D.\ Petritis.
\newblock Markov chains in a wedge with excitable boundaries, preprint
  université de {R}ennes 1, 2000.

\bibitem{MohWoe}
B.\ Mohar and W.\ Woess.
\newblock A survey on spectra of infinite graphs.
\newblock {\em Bull.\ London Math.\ Soc.}, 21:209--234, 1989.

\bibitem{Pai}
A.\ Pais.
\newblock {\em Subtle is the Lord\ldots}.
\newblock Oxford University Press, Oxford, 1982.

\bibitem{Soa}
P.\ Soardi.
\newblock {\em Potential theory of infinite newtorks}.
\newblock Springer-Verlag, Berlin, 1994.

\bibitem{Spi}
F.\ Spitzer.
\newblock {\em Principles of random walk, 2nd edition}.
\newblock Springer-Verlag, Berlin, 2001.

\bibitem{Woe}
W.\ Woess.
\newblock {\em Random walks on infinite graphs and groups}.
\newblock Cambridge University Press, Cambridge, 2000.

\end{thebibliography}