@article{10_2140_agt_2004_4_1253,
     author = {Hatcher, Allen and Vogtmann, Karen},
     title = {Homology stability for outer automorphism groups of free groups},
     journal = {Algebraic and Geometric Topology},
     pages = {1253--1272},
     year = {2004},
     volume = {4},
     number = {2},
     doi = {10.2140/agt.2004.4.1253},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2004.4.1253/}
}