@article{DAN_1966_167_6_a2,
     author = {R. S. Ismagilov and V. V. Martynov},
     title = {A criterion for the discreteness of the spectrum of a selfadjoint system of differential equations of the first order with slowly varying coefficients},
     journal = {Doklady Akademii Nauk},
     pages = {1223--1225},
     publisher = {mathdoc},
     volume = {167},
     number = {6},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_167_6_a2/}
}