@article{DAN_1962_142_6_a5,
     author = {R. S. Ismagilov},
     title = {Self-adjointness conditions of higher-order differential operators},
     journal = {Doklady Akademii Nauk},
     pages = {1239--1242},
     publisher = {mathdoc},
     volume = {142},
     number = {6},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_142_6_a5/}
}