Slyusarchuk, V. Yu. 2014. “Conditions for Almost Periodicity of Bounded Solutions of Nonlinear Differential Equations Unsolved With Respect to the Derivative”. Ukrains’kyi Matematychnyi Zhurnal 66 (3): 384–393. https://umj.imath.kiev.ua/index.php/umj/article/view/2140.