@article{DE_1981_17_3_a9,
     author = {V. G. Litvinov},
     title = {A modification of the {Ritz} method for variational equations and its applications to boundary value problems with mixed boundary conditions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {519--526},
     publisher = {mathdoc},
     volume = {17},
     number = {3},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_3_a9/}
}