@article{SM_1979_35_6_a5,
     author = {G. L. Kharatishvili and T. A. Tadumadze},
     title = {Nonlinear optimal control systems with variable time lags},
     journal = {Sbornik. Mathematics},
     pages = {863--881},
     year = {1979},
     volume = {35},
     number = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1979_35_6_a5/}
}