Islomov, B. I., et al. “On a Frankl-Type Boundary-Value Problem for a Mixed-Type Degenerating Equation”. Ukrains’kyi Matematychnyi Zhurnal, vol. 71, no. 10, Feb. 2026, pp. 1347-59, https://doi.org/10.3842/umzh.v71i10.1519.