@article{COCV_2015__21_4_958_0,
     author = {Ardentov, A.A. and Sachkov, Yu.L.},
     title = {Cut time in sub-riemannian problem on engel group},
     journal = {ESAIM: Control, Optimisation and Calculus of Variations},
     pages = {958--988},
     publisher = {EDP-Sciences},
     volume = {21},
     number = {4},
     year = {2015},
     doi = {10.1051/cocv/2015027},
     mrnumber = {3395751},
     zbl = {1330.53044},
     language = {en},
     url = {http://www.numdam.org/articles/10.1051/cocv/2015027/}
}