“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”. Neliniini Kolyvannya 11, no. 3 (September 29, 2008): 421–436. Accessed January 21, 2026. https://twinhead.imath.kiev.ua/index.php/nosc/article/view/490.