@article{10_4064_cm_52_2_285_287,
     author = {Leonard F. Richardson},
     title = {N-step nilpotent {Lie} groups with flat {Kirillov} orbits},
     journal = {Colloquium Mathematicum},
     pages = {285--287},
     publisher = {mathdoc},
     volume = {52},
     number = {2},
     year = {1987},
     doi = {10.4064/cm-52-2-285-287},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-52-2-285-287/}
}