“…There, suitably modified defining systems of the underlying bifurcations are manipulated in order to obtain existence and closeness results. Such defining systems for the computation of Hopf points are studied in [2,3,10,12,24,27], and for Hopf-Hopf bifurcations in [1,9,29]. A broad overview of defining systems for various types of bifurcations can be found in [8].…”