@article{DE_1976_12_6_a18,
     author = {V. S. Ermolin},
     title = {The existence of a definitely positive first integral},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1123--1124},
     publisher = {mathdoc},
     volume = {12},
     number = {6},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_6_a18/}
}