@article{DAN_1983_273_5_a9,
     author = {Y. P. Popov and A. V. Timofeev},
     title = {Controllability on a subspace, and adaptive modal regulators},
     journal = {Doklady Akademii Nauk},
     pages = {1070--1073},
     year = {1983},
     volume = {273},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1983_273_5_a9/}
}