@article{VUU_2015_25_4_a4,
     author = {I. V. Lisachenko and V. I. Sumin},
     title = {On singular controls of a~maximum principle for the problem of the {Goursat--Darboux} system optimization},
     journal = {Vestnik Udmurtskogo universiteta. Matematika, mehanika, kompʹ\^uternye nauki},
     pages = {483--491},
     publisher = {mathdoc},
     volume = {25},
     number = {4},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VUU_2015_25_4_a4/}
}