@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}
}