@article{SM_2021_212_7_a0,
     author = {E. R. Avakov and G. G. Magaril-Il'yaev},
     title = {Local controllability and optimality},
     journal = {Sbornik. Mathematics},
     pages = {887--920},
     year = {2021},
     volume = {212},
     number = {7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2021_212_7_a0/}
}