@article{DE_1975_11_4_a7,
     author = {S. T. Zavalishchin and A. N. Sesekin},
     title = {Singular solutions in optimization problems for dynamical systems with a quadratic quality test},
     journal = {Differencialʹnye uravneni\^a},
     pages = {665--671},
     publisher = {mathdoc},
     volume = {11},
     number = {4},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1975_11_4_a7/}
}