Ptashnik, B. I., and I. R. Tymkiv. 2013. “Multipoint Problem for <i>B</I&gt;-Parabolic Equations”. Ukrains’kyi Matematychnyi Zhurnal 65 (3), 418-29. https://umj.imath.kiev.ua/index.php/umj/article/view/2428.