M. E. Bekka and A. Valette, Group cohomology, harmonic functions and the first L 2 -Betti number, Potential Analysis, vol.6, issue.4, pp.313-326, 1997.
DOI : 10.1023/A:1017974406074

A. Canton, J. L. Fernandez, D. Pestana, and J. M. Rodriguez, On harmonic functions on trees, Potential Analysis, pp.15-199, 2001.

W. J. Floyd, Group completions and limit sets of Kleinian groups, Inventiones Mathematicae, vol.166, issue.3, pp.205-218, 1980.
DOI : 10.1007/BF01418926

V. Kaimanovich and W. Woess, The Dirichlet problem at infinity for random walks on graphs with a strong isoperimetric inequality, Probability Theory and Related Fields, vol.68, issue.3-4, pp.445-466, 1992.
DOI : 10.1007/BF01192066

A. Karlsson, Boundaries and random walks on finitely generated infinite groups, Arkiv för Matematik, pp.41-295, 2003.
DOI : 10.1007/BF02390817
URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.487.1189

A. Karlsson, Free Subgroups of Groups with Nontrivial Floyd Boundary, Communications in Algebra, vol.214, issue.11, pp.31-5361, 2003.
DOI : 10.1081/AGB-120023961

A. Karlsson, G. A. Noskov, R. Kaufman, and J. Wu, Some groups having only elementary actions on metric spaces with hyperbolic boundaries Fatou theorem of p-harmonic functions on trees Ann, Probab, pp.28-1138, 2000.

J. Roe, Hyperbolic metric spaces and the exotic cohomology Novikov conjecture, K-Theory, vol.4, issue.6, pp.501-512, 1991.
DOI : 10.1007/BF00538881

P. M. Soardi, Potential Theory in Infinte Networks, Lecture Notes in Math, vol.1590, 1994.

E. Specker, Die erste Cohomologiegruppe von ??berlagerungen und Homotopie-Eigenschaften dreidimensionaler Mannigfaltigkeiten, Commentarii Mathematici Helvetici, vol.23, issue.1, pp.303-333, 1949.
DOI : 10.1007/BF02565606

W. Woess, Random Walks on Infinite Graphs and Groups, Cambridge Tracts in Math, 2000.