@article{CMH_1974__49_139587,
     author = {Ralph Strebel},
     title = {Homological {Methods} {Applied} to the {Derived} {Series} of {Groups}},
     journal = {Commentarii mathematici Helvetici},
     pages = {302--332},
     publisher = {mathdoc},
     volume = {49},
     year = {1974},
     zbl = {0288.20066},
     url = {http://geodesic.mathdoc.fr/item/CMH_1974__49_139587/}
}