@article{DE_1989_25_11_a17,
     author = {V. A. Il'in and K. V. Mal'kov and E. I. Moiseev},
     title = {The basis property of systems of root functions of nonselfadjoint operators, and integrability of nonlinear evolution systems that are associated with the {Lax} representation. {I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1956--1970},
     publisher = {mathdoc},
     volume = {25},
     number = {11},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_11_a17/}
}