@article {brockett73lie,
    AUTHOR = {Brockett, R. W.},
     TITLE = {Lie theory and control systems defined on spheres},
      NOTE = {Lie algebras: applications and computational methods (Conf.,
              Drexel Univ., Philadelphia, Pa., 1972)},
   JOURNAL = {SIAM J. Appl. Math.},
    VOLUME = {25},
      YEAR = {1973},
     PAGES = {213--225}
}