A necessary condition for the existence of periodical solutions of a differential system
Julka Knežević Miljanović
Abstract
The problem of necessary conditions for the existence of
periodical solutions of the system $X'=\f(t)P(X)+Q(t)$ is considered, where
$\f(t)$, $Q_i(t)$ ($i=1,\dots,n$) are continuous functions belonging to
certain classes.