@article{urn:eudml:doc:39684, title = {Monotonicity of the period map of a non-Hamiltonian center.}, journal = {Collectanea Mathematica}, volume = {45}, year = {1994}, pages = {177-182}, zbl = {0812.34018}, mrnumber = {MR1316935}, language = {en}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:39684} }
Billeke, Jorge; Sáez, Eduardo. Monotonicity of the period map of a non-Hamiltonian center.. Collectanea Mathematica, Tome 45 (1994) pp. 177-182. http://gdmltest.u-ga.fr/item/urn:eudml:doc:39684/