I'm reading about the PoincaréBendixson theorem in the plane, I really liked the theorem. I have seen common applications in Sotomayor and Perko's book. But I would like to know what other applications outside of the common literature (mentioned above) there are, I mean interesting applications that you create valuable. If possible, mention a reference to your example. Thank you very much.

1$\begingroup$ this is really way too unfocused for this site. $\endgroup$– Carlo BeenakkerMar 10 at 15:34

1$\begingroup$ A related question on math.stackexchange: math.stackexchange.com/questions/326351/… $\endgroup$– AGenevoisMar 10 at 16:19

$\begingroup$ Does periodicity for solutions of the LotkaVolterra equations count? Though there are more elementary arguments for that. $\endgroup$– ThiKuMar 11 at 15:36

$\begingroup$ Now I am busy with work, later I will edit my question to list all the applications that I have managed to find along with your reference, I think that way you could help me much better. $\endgroup$– ZaragosaMar 11 at 21:03