@article{10_2140_agt_2008_8_2131,
     author = {Calegari, Danny and Zhuang, Dongping},
     title = {Large scale geometry of commutator subgroups},
     journal = {Algebraic and Geometric Topology},
     pages = {2131--2146},
     year = {2008},
     volume = {8},
     number = {4},
     doi = {10.2140/agt.2008.8.2131},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2008.8.2131/}
}