@article{AIHPB_1995__31_1_59_0,
     author = {Bougerol, Philippe and Elie, Laure},
     title = {Existence of positive harmonic functions on groups and on covering manifolds},
     journal = {Annales de l'I.H.P. Probabilit\'es et statistiques},
     pages = {59--80},
     publisher = {Gauthier-Villars},
     volume = {31},
     number = {1},
     year = {1995},
     mrnumber = {1340031},
     zbl = {0833.22006},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPB_1995__31_1_59_0/}
}