@article{PMIHES_1978__48__39_0, author = {Breen, Lawrence}, title = {Extensions du groupe additif}, journal = {Publications Math\'ematiques de l'IH\'ES}, pages = {39--125}, year = {1978}, publisher = {Institut des Hautes Etudes Scientifiques}, volume = {48}, mrnumber = {516914}, zbl = {0404.14018}, language = {fr}, url = {https://www.numdam.org/item/PMIHES_1978__48__39_0/} }