@article{FAA_1989_23_2_a0,
     author = {I. M. Gel'fand and I. S. Zakharevich},
     title = {Spectral theory of a pencil of skew-symmetric differential operators of third order on $S^1$},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {1--11},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1989_23_2_a0/}
}