@article{MZM_2020_107_4_a11,
     author = {A. A. Vladimirov},
     title = {Variational {Principles} for {Self-Adjoint} {Hamiltonian} {Systems}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {633--636},
     publisher = {mathdoc},
     volume = {107},
     number = {4},
     year = {2020},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2020_107_4_a11/}
}