@article{10_4171_ggd_99,
     author = {Gilbert Baumslag and Charles F. Miller III and Gretchen Ostheimer},
     title = {Subgroups of free metabelian groups},
     journal = {Groups, geometry, and dynamics},
     pages = {657--679},
     year = {2010},
     volume = {4},
     number = {4},
     doi = {10.4171/ggd/99},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/99/}
}