“…Canonical systems are important objects of analysis, being perhaps the most important class of the one-dimensional Hamiltonian systems and including (as subclasses) several classical equations. They have been actively studied in many already classical as well as in various recent works (see, e.g., [1,5,7,12,13,18,20,[22][23][24][25][30][31][32][36][37][38]41,42] and numerous references therein).…”