@article{DE_1973_9_11_a28,
     author = {V. I. Blagodatskikh},
     title = {Letter to the editors: {``A} sufficient optimality condition'' {(Differencial'nye} {Uravnenija} \textbf{9} (1973), 416--422)},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2112},
     publisher = {mathdoc},
     volume = {9},
     number = {11},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_11_a28/}
}