Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MZ_1950__53_169184, author = {G. BIRKHOFF}, title = {Extensions of {Lie} {Groups}}, journal = {Mathematische Zeitschrift}, pages = {226--235}, publisher = {mathdoc}, volume = {53}, year = {1950}, zbl = {0039.02003}, url = {http://geodesic.mathdoc.fr/item/MZ_1950__53_169184/} }
G. BIRKHOFF. Extensions of Lie Groups. Mathematische Zeitschrift, Tome 53 (1950), pp. 226-235. http://geodesic.mathdoc.fr/item/MZ_1950__53_169184/