@article{GDZPPN002093537, title = {Biinvariant Operators on Nilpotent Lie Groups.}, journal = {Inventiones mathematicae}, volume = {41}, year = {1977}, pages = {259-264}, zbl = {0373.58009}, url = {http://dml.mathdoc.fr/item/GDZPPN002093537} }
Wigner, David. Biinvariant Operators on Nilpotent Lie Groups.. Inventiones mathematicae, Tome 41 (1977) pp. 259-264. http://gdmltest.u-ga.fr/item/GDZPPN002093537/