@article{MS2_1959__7_165713,
     author = {B.H. Neumann and G. Baumslag and W.W. Boone},
     title = {Some {Unsolvable} {Problems} about {Elements} and {Subgroups} of {Groups.}},
     journal = {Mathematica Scandinavica},
     pages = {191--201},
     publisher = {mathdoc},
     volume = {7},
     year = {1959},
     zbl = {0104.00704},
     url = {http://geodesic.mathdoc.fr/item/MS2_1959__7_165713/}
}