@article{DAN_1980_255_4_a0,
     author = {Yu. Sh. Abramov},
     title = {Duality in extremal problems generated by spectral problems for operator pencils},
     journal = {Doklady Akademii Nauk},
     pages = {777--780},
     publisher = {mathdoc},
     volume = {255},
     number = {4},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_255_4_a0/}
}