@article{GDZPPN002485931, title = {Surfaces and the Second Homology of a Group.}, journal = {Monatshefte f\"ur Mathematik}, volume = {104}, year = {1987}, pages = {247-254}, url = {http://dml.mathdoc.fr/item/GDZPPN002485931} }
Zimmermann, Bruno. Surfaces and the Second Homology of a Group.. Monatshefte für Mathematik, Tome 104 (1987) pp. 247-254. http://gdmltest.u-ga.fr/item/GDZPPN002485931/