@article{10_4171_ggd_28,
     author = {Dan Segal},
     title = {Variations on a theme of {Burns} and {Medvedev}},
     journal = {Groups, geometry, and dynamics},
     pages = {661--668},
     year = {2007},
     volume = {1},
     number = {4},
     doi = {10.4171/ggd/28},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/28/}
}