GordevskiiV. D., and GukalovA. A. “Approximate Solutions of the Boltzmann Equation With Infinitely Many Modes”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 69, no. 3, Mar. 2017, pp. 311-23, http://umj.imath.kiev.ua/index.php/umj/article/view/1698.