@article{COCV_2012__18_3_774_0,
     author = {Li, Shun-Jie and Respondek, Witold},
     title = {Flat outputs of two-input driftless control systems},
     journal = {ESAIM: Control, Optimisation and Calculus of Variations},
     pages = {774--798},
     publisher = {EDP-Sciences},
     volume = {18},
     number = {3},
     year = {2012},
     doi = {10.1051/cocv/2011181},
     mrnumber = {3041664},
     zbl = {1252.93041},
     language = {en},
     url = {http://www.numdam.org/articles/10.1051/cocv/2011181/}
}