@article{DE_1983_19_9_a5,
     author = {A. D. Morozov and E. L. Fedorov},
     title = {On the investigation of equations with one degree of freedom, close to nonlinear integrable ones},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1511--1516},
     publisher = {mathdoc},
     volume = {19},
     number = {9},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_9_a5/}
}