@article{10_4171_ggd_8,
     author = {Vincent Guirardel and Gilbert Levitt},
     title = {Deformation spaces of trees},
     journal = {Groups, geometry, and dynamics},
     pages = {135--181},
     year = {2007},
     volume = {1},
     number = {2},
     doi = {10.4171/ggd/8},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/8/}
}