@article{article2500e30b,
title   = {Global properties of a class of vector fields in the plane},
author = {Bergamasco, Adalberto Panobianco and Cordaro, Paulo Domingos and Hounie, Jorge},
year = {1988},
doi = {10.1016/0022-0396(88)90001-0},
journal   = {Journal of Differential Equations}
}