@article{10_1017_S0017089500006637,
     author = {Ellis, G. J.},
     title = {Non-abelian exterior products of groups and exact sequences in the homology of groups},
     journal = {Glasgow mathematical journal},
     pages = {13--19},
     year = {1987},
     volume = {29},
     number = {1},
     doi = {10.1017/S0017089500006637},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500006637/}
}