- Torsten Lindström, Handbook of the Mathematics of the Arts and Sciences, 2021, 2291
- Stephen Lynch, Dynamical Systems with Applications using MAPLE, 2001, 181
- N. B. Medvedeva, “On the analytic solvability of the problem of distinguishing between center and focus”, Proc. Steklov Inst. Math., 254, № 1, 2006, 7
- G. A. Kolyutsky, “Upper bounds on the number of limit cycles in generalized Liénard equations of odd type”, Dokl. Math., 81, № 2, 2010, 176
- Stephen Lynch, Dynamical Systems with Applications using Python, 2018, 271
- Jibin Li, H. S. Y. Chan, K. W. Chung, “Some lower bounds forH(n) in Hilbert’s 16th problem”, Qual. Th. Dyn. Syst., 3, № 2, 2002, 345
- Daniel Panazzolo, “PSL(2, ℂ), the exponential and some new free groups”, The Quarterly Journal of Mathematics, 69, № 1, 2018, 75
- Antonio Algaba, Cristóbal García, Jaume Giné, “Geometric Criterium in the Center Problem”, Mediterr. J. Math., 13, № 5, 2016, 2593
- VÍCTOR MAÑOSA, “ON THE CENTER PROBLEM FOR DEGENERATE SINGULAR POINTS OF PLANAR VECTOR FIELDS”, Int. J. Bifurcation Chaos, 12, № 04, 2002, 687
- Xiang Zhang, “On the Limit Cycles of Quadratic Differential Systems”, Acta Math Sinica, 18, № 4, 2002, 803