@article{1077375367, author = {Ostberg, D. R.}, title = {Relative group extensions and kernels}, journal = {Duke Math. J.}, volume = {31}, number = {1}, year = {1964}, pages = { 529-537}, language = {en}, url = {http://dml.mathdoc.fr/item/1077375367} }
Ostberg, D. R. Relative group extensions and kernels. Duke Math. J., Tome 31 (1964) no. 1, pp. 529-537. http://gdmltest.u-ga.fr/item/1077375367/