@article{IM_1969__7_141958,
     author = {R.A. NORMAN},
     title = {Dehn's {Lemma} for {Certain} {4-Manifolds.}},
     journal = {Inventiones mathematicae},
     pages = {143--147},
     publisher = {mathdoc},
     volume = {7},
     year = {1969},
     zbl = {0181.51602},
     url = {http://geodesic.mathdoc.fr/item/IM_1969__7_141958/}
}