BugirM. “Theorems on the Average Values and Non-Oscillating Character of the Solutions of the Partial Differential Equations in the Spaces $E^n$ and $P^n$ ”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 44, no. 11, Mar. 2024, pp. 1477-83, https://umj.imath.kiev.ua/index.php/umj/article/view/8248.