TY - JOUR AU - V. I. Blagodatskikh TI - Letter to the editors: ``A sufficient optimality condition'' (Differencial'nye Uravnenija \textbf{9} (1973), 416--422) JO - Differencialʹnye uravneniâ PY - 1973 SP - 2112 VL - 9 IS - 11 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/DE_1973_9_11_a28/ LA - ru ID - DE_1973_9_11_a28 ER -