@article{article4ef64910,
title   = {Positive quadratic differential forms: topological equivalence through Newton polyhedra},
author = {Gutierrez, Carlos and Oliveira, Regilene Delazari dos Santos and Teixeira, M. A},
year = {2006},
doi = {10.1007/s10883-006-0003-1},
journal   = {Journal of Dynamical and Control Systems}
}