@article{DAN_1960_134_4_a4,
     author = {P. I. Lizorkin},
     title = {The {Dirichlet} principle for the {Beltrami} equation in a semi-space},
     journal = {Doklady Akademii Nauk},
     pages = {761--764},
     publisher = {mathdoc},
     volume = {134},
     number = {4},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_134_4_a4/}
}