@article{DE_1973_9_9_a20,
     author = {M. M. Kopets},
     title = {The optimal control of a system with free initial and final states in {Hilbert} space},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1728--1729},
     publisher = {mathdoc},
     volume = {9},
     number = {9},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_9_a20/}
}