@article{DE_1985_21_2_a21,
     author = {V. Kh. Kovachev},
     title = {Some bilinear invariants of two-dimensional autonomous systems of ordinary differential equations with rational right-hand side},
     journal = {Differencialʹnye uravneni\^a},
     pages = {331--334},
     publisher = {mathdoc},
     volume = {21},
     number = {2},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1985_21_2_a21/}
}