@article{SM_1977_32_4_a1,
     author = {V. I. Bernik},
     title = {Induced extremal surfaces},
     journal = {Sbornik. Mathematics},
     pages = {413--421},
     publisher = {mathdoc},
     volume = {32},
     number = {4},
     year = {1977},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1977_32_4_a1/}
}