@article{JEMS_2015_17_1_a3,
     author = {Michael Magee},
     title = {Quantitative spectral gap for thin groups of hyperbolic isometries},
     journal = {Journal of the European Mathematical Society},
     pages = {151--187},
     publisher = {mathdoc},
     volume = {17},
     number = {1},
     year = {2015},
     doi = {10.4171/jems/500},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/500/}
}