Voir la notice de l'article provenant de la source Math-Net.Ru
@article{IVM_1961_2_a4, author = {F. M. Kirillova}, title = {The problem of existence of optimal trajectories of nonlinear systems}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {41--53}, publisher = {mathdoc}, number = {2}, year = {1961}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1961_2_a4/} }
F. M. Kirillova. The problem of existence of optimal trajectories of nonlinear systems. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 2 (1961), pp. 41-53. http://geodesic.mathdoc.fr/item/IVM_1961_2_a4/