@article{DAN_1973_209_5_a9,
     author = {V. A. Yakubovich},
     title = {Minimization of quadratic functionals under quadratic constraints and the necessity of a frequency condition in the quadratic criterion for absolute stability of nonlinear control systems},
     journal = {Doklady Akademii Nauk},
     pages = {1039--1042},
     publisher = {mathdoc},
     volume = {209},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_209_5_a9/}
}