@article{GT_2009_13_4_a6,
     author = {Rafi, Kasra and Schleimer, Saul},
     title = {Covers and the curve complex},
     journal = {Geometry & topology},
     pages = {2141--2162},
     publisher = {mathdoc},
     volume = {13},
     number = {4},
     year = {2009},
     doi = {10.2140/gt.2009.13.2141},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/gt.2009.13.2141/}
}