@article{MZM_2020_108_6_a6,
     author = {Yu. L. Sachkov},
     title = {Coadjoint {Orbits} and {Time-Optimal} {Problems} for {Step-}$2$ {Free} {Nilpotent} {Lie} {Groups}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {899--910},
     publisher = {mathdoc},
     volume = {108},
     number = {6},
     year = {2020},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2020_108_6_a6/}
}