@article{DE_2005_41_1_a5,
     author = {A. A. Grin' and L. A. Cherkas},
     title = {Extrema of the {Andronov--Hopf} function of a polynomial {Lienard} system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {50--60},
     publisher = {mathdoc},
     volume = {41},
     number = {1},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2005_41_1_a5/}
}