@article{SM_2013_204_11_a4,
     author = {M. I. Zelikin and D. D. Kiselev and L. V. Lokutsievskii},
     title = {Optimal control and {Galois} theory},
     journal = {Sbornik. Mathematics},
     pages = {1624--1638},
     publisher = {mathdoc},
     volume = {204},
     number = {11},
     year = {2013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2013_204_11_a4/}
}