@incollection {MR1972790,
    AUTHOR = {Kawski, Matthias},
     TITLE = {The combinatorics of nonlinear controllability and
              noncommuting flows},
 BOOKTITLE = {Mathematical control theory, {P}art 1, 2 ({T}rieste, 2001)},
    SERIES = {ICTP Lect. Notes, VIII},
     PAGES = {223--311 (electronic)},
 PUBLISHER = {Abdus Salam Int. Cent. Theoret. Phys., Trieste},
      YEAR = {2002},
   MRCLASS = {93-02 (93B05)},
  MRNUMBER = {MR1972790},
}