@article{SM_2019_210_1_a0,
     author = {E. R. Avakov and G. G. Magaril-Il'yaev},
     title = {Controllability and second-order necessary conditions for optimality},
     journal = {Sbornik. Mathematics},
     pages = {1--23},
     publisher = {mathdoc},
     volume = {210},
     number = {1},
     year = {2019},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2019_210_1_a0/}
}