Zhao, Yulin; Zhang, Zhifen An estimate of the number of zeros of Abelian integrals for cubic vector fields with cuspidal loop. (English) Zbl 0967.34027 Ann. Differ. Equations 14, No. 2, 434-445 (1998). MSC: 34C08 14K20 34C05 34C23 37G15 PDFBibTeX XMLCite \textit{Y. Zhao} and \textit{Z. Zhang}, Ann. Differ. Equations 14, No. 2, 434--445 (1998; Zbl 0967.34027)
Zhang, Zhifen; Li, Chengzhi On the number of limit cycles of a class of quadratic Hamiltonian systems under quadratic perturbations. (English) Zbl 0948.34020 Adv. Math., Beijing 26, No. 5, 445-460 (1997). Reviewer: Dmitry Turaev (Berlin) MSC: 34C07 37G15 34C23 PDFBibTeX XMLCite \textit{Z. Zhang} and \textit{C. Li}, Adv. Math., Beijing 26, No. 5, 445--460 (1997; Zbl 0948.34020)