MarkovskiiA. I. (1993) “On the $L_p -L_q$- estimates for the solutions of certain hyperbolic equations”, Ukrains’kyi Matematychnyi Zhurnal, 45(7), pp. 992–1008. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5893 (Accessed: 27July2024).