Casas-Sánchez, O. F. ., Galeano-Peñaloza, J. ., & Rodríguez-Vega, J. J. . (2021). $p$-Adic Markov process and the problem of the first return over balls. Ukrains’kyi Matematychnyi Zhurnal, 73(7), 902-912. https://doi.org/10.37863/umzh.v73i7.464