Reversibility of the nonlinear operator $(\mathcal{L}x)(t)=H\bigl(x(t),\frac{d x(t)}{dt}\bigr)$ in the space of functions bounded on the real axis. (2008). Neliniini Kolyvannya, 11(3), 421-436. https://twinhead.imath.kiev.ua/index.php/nosc/article/view/490