CHEN Yanyan, . The Number of Critical Periods for a Planar Polynomial Systems[J]. Acta Scientiarum Naturalium Universitatis SunYatseni, 2009,48(4):130-132.
CHEN Yanyan, . The Number of Critical Periods for a Planar Polynomial Systems[J]. Acta Scientiarum Naturalium Universitatis SunYatseni, 2009,48(4):130-132.DOI: