@article{10_1090_S0894_0347_2011_00711_X,
     author = {Agol, Ian and Liu, Yi},
     title = {Presentation length and {Simon\^a€™s} conjecture},
     journal = {Journal of the American Mathematical Society},
     pages = {151--187},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {2012},
     doi = {10.1090/S0894-0347-2011-00711-X},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-2011-00711-X/}
}