@article{JEMS_2009_11_2_a3,
     author = {Dubi Kelmer and Peter Sarnak},
     title = {Strong spectral gaps for compact quotients of products of {PSL(2,\ensuremath{\mathbb{R}})}},
     journal = {Journal of the European Mathematical Society},
     pages = {283--313},
     publisher = {mathdoc},
     volume = {11},
     number = {2},
     year = {2009},
     doi = {10.4171/jems/151},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/151/}
}