@article{AIHPA_1970__13_3_215_0, author = {Gille, J. F.}, title = {An exponentiation theorem for unbounded derivations}, journal = {Annales de l'institut Henri Poincar\'e. Section A, Physique Th\'eorique}, pages = {215--220}, publisher = {Gauthier-Villars}, volume = {13}, number = {3}, year = {1970}, mrnumber = {279595}, zbl = {0204.44401}, language = {en}, url = {http://www.numdam.org/item/AIHPA_1970__13_3_215_0/} }