@article{DE_1983_19_9_a18,
     author = {M. Yu. Bogdanova and N. F. Naumovich},
     title = {Differential equations with an area first integral},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1613--1617},
     publisher = {mathdoc},
     volume = {19},
     number = {9},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_9_a18/}
}