Gao, Suzhi; Wang, Xuejin A kind of quadratic differential system with a fine focus of order 2. (Chinese. English summary) Zbl 0803.34015 J. Beijing Norm. Univ., Nat. Sci. 30, No. 1, 12-15 (1994). MSC: 34C05 × Cite Format Result Cite Review PDF
Gao, Suzhi; Suo, Guangjian Two-uniqueness of limit cycles encircling three critical points of Liénard’s equation. (Chinese. English summary) Zbl 0776.34023 J. Beijing Norm. Univ., Nat. Sci. 29, No. 1, 30-34 (1993). MSC: 34C05 × Cite Format Result Cite Review PDF
Gao, Suzhi On the existence of at most 2 limit cycles surrounding multiple singular points for Liénard equation. (Chinese. English summary) Zbl 0768.34016 J. Beijing Norm. Univ., Nat. Sci. 28, No. 3, 301-305 (1992). MSC: 34C05 × Cite Format Result Cite Review PDF