@article{VUU_2011_2_a3,
     author = {I. V. Lisachenko and V. I. Sumin},
     title = {The maximum principle for terminal optimization problem connected with {Goursat{\textendash}Darboux} system in the class of functions having summable mixed derivatives},
     journal = {Vestnik Udmurtskogo universiteta. Matematika, mehanika, kompʹ\^uternye nauki},
     pages = {52--67},
     year = {2011},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VUU_2011_2_a3/}
}