@article{MZM_1977_21_6_a9,
     author = {V. I. Khrabustovskii},
     title = {The discrete spectrum of perturbed differential operators of arbitrary order with periodic matrix coefficients},
     journal = {Matemati\v{c}eskie zametki},
     pages = {829--838},
     publisher = {mathdoc},
     volume = {21},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_21_6_a9/}
}