@article{GDZPPN002087553, title = {Dehn's Lemma for Certain 4-Manifolds.}, journal = {Inventiones mathematicae}, volume = {9}, year = {1969}, pages = {143-147}, zbl = {0181.51602}, url = {http://dml.mathdoc.fr/item/GDZPPN002087553} }
NORMAN, R.A. Dehn's Lemma for Certain 4-Manifolds.. Inventiones mathematicae, Tome 9 (1969) pp. 143-147. http://gdmltest.u-ga.fr/item/GDZPPN002087553/