MARKOVSKII, A. I. On the $L_p -L_q$- estimates for the solutions of certain hyperbolic equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 7, p. 992–1008, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5893. Acesso em: 5 dec. 2025.