Geodesic
An example of eqations $\frac{dw}{dz}=\frac{P_n(z,w)}{Q_n(z,w)}$ having a~countable number of limit cycles and arbitrarily large Petrovskii--Landis genus
Sbornik. Mathematics, Tome 9 (1969) no. 3, pp. 365-378

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In this work we construct an open set $V$ in the space of coefficients $A_n$ of the equations $\frac{dw}{dz}=\frac{P_n(z,w)}{Q_n(z,w)}$ such that on the solutions of an arbitrary equation $\alpha\in V$ there exist a countable number of homotopically distinct limit cycles. Also, for each natural number $N$ we construct an open set $V_N\subset A_n$ such that an arbitrary equation $\alpha\in V_N$ has a Petrovskii–Landis genus which exceeds $N$. Bibliography: 9 titles. 
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     author = {Yu. S. Ilyashenko},
     title = {An example of eqations $\frac{dw}{dz}=\frac{P_n(z,w)}{Q_n(z,w)}$ having a~countable number of limit cycles and arbitrarily large {Petrovskii--Landis} genus},
     journal = {Sbornik. Mathematics},
     pages = {365--378},
     publisher = {mathdoc},
     volume = {9},
     number = {3},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_9_3_a5/}
}
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Yu. S. Ilyashenko. An example of eqations $\frac{dw}{dz}=\frac{P_n(z,w)}{Q_n(z,w)}$ having a~countable number of limit cycles and arbitrarily large Petrovskii--Landis genus. Sbornik. Mathematics, Tome 9 (1969) no. 3, pp. 365-378. http://geodesic.mathdoc.fr/item/SM_1969_9_3_a5/