S. I. Podolinnyi, “Perturbation of homogeneous parabolic pseudodifferential equations by locally unbounded vector fields”, Ukr. Mat. Zhurn., vol. 49, no. 11, pp. 1561–1566, Nov. 1997, Accessed: Apr. 13, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5157