@article{BASM_2003_1_a3,
     author = {Leonid A. Cherkas and Joan C. Art\'es and Jaume Llibre},
     title = {Quadratic  systems with limit cycles of normal size},
     journal = {Buletinul Academiei de \c{S}tiin\c{t}e a Republicii Moldova. Matematica},
     pages = {31--46},
     publisher = {mathdoc},
     number = {1},
     year = {2003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BASM_2003_1_a3/}
}