@article{CRMATH_2007__344_2_109_0,
     author = {Sklyar, Grigory and Ignatovich, Svetlana},
     title = {Description of all privileged coordinates in the homogeneous approximation problem for nonlinear control systems},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {109--114},
     publisher = {Elsevier},
     volume = {344},
     number = {2},
     year = {2007},
     doi = {10.1016/j.crma.2006.11.016},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2006.11.016/}
}