1. On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or centre type;Bautin N. N.;Mat. Sb.,1952
2. On Non-Linear Differential Equations of the Second Order: I. the Equation y¨ − k
(1-y
2
)y˙ + y
= b
λk
cos(λl
+ α), k
Large
3. Sur les cycles limites
4. Non‐accumulation des cycles‐limites I;Écalle J.;C. R. Acad. Sci. Paris Sér. I Math.,1987
5. Non‐accumulation des cycles‐limites II;Écalle J.;C. R. Acad. Sci. Paris Sér. I Math.,1987