IvasyshenS. D., and LayukV. V. 2011. “Fundamental Solutions of the Cauchy Problem for Some Degenerate Parabolic Equations of the Kolmogorov Type”. Ukrains’kyi Matematychnyi Zhurnal 63 (11), 1469-1500. https://umj.imath.kiev.ua/index.php/umj/article/view/2819.