@article{DAN_1977_235_5_a10,
     author = {V. K. Romanko},
     title = {On boundary value problems for differential operator equations that are not solved for the highest derivative},
     journal = {Doklady Akademii Nauk},
     pages = {1030--1033},
     publisher = {mathdoc},
     volume = {235},
     number = {5},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_235_5_a10/}
}