Limit cycles of quadratic systems in the plane
\textit{C. Chicone} and the reviewer [Am. Math. Mon. 89, 167-178 (1982; Zbl 0466.34011)] suggested making computer plots of all the known examples exhibiting the six distributions of limit cycles of quadratic systems. This paper contains numerical plots of all of the known limit cycle distributions except (1,2)-distribution and adds a bit to the knowledge of limit cycle configurations of quadratic systems in the plane. The fact that there are exactly (1,1)-distributions of limit cycles was established by the reviewer [J. Sichuan Univ., Nat. Sci. Ed. 1983, No.3, 9-13 (1983; Zbl 0513.34035)] earlier than in the paper of \textit{L. M. Perko} and \textit{S. Shu} [J. Differ. Equations 53, 146-171 (1984; Zbl 0493.34025)].
scientific article; zbMATH DE number 3879327