@article{SM_1973_21_1_a3,
     author = {A. N. Kozhevnikov},
     title = {Spectral problems for pseudodifferential systems elliptic in the {Douglis--Nirenberg} sense, and their applications},
     journal = {Sbornik. Mathematics},
     pages = {63--90},
     publisher = {mathdoc},
     volume = {21},
     number = {1},
     year = {1973},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1973_21_1_a3/}
}