@article{MZ_1990__205_3_174184,
     author = {Marc Burger},
     title = {Small eigenvalues of {Riemann} surfaces and graphs.},
     journal = {Mathematische Zeitschrift},
     pages = {395--420},
     publisher = {mathdoc},
     volume = {205},
     number = {3},
     year = {1990},
     zbl = {0729.58050},
     url = {http://geodesic.mathdoc.fr/item/MZ_1990__205_3_174184/}
}