A logarithmic class of semilinear wave equations. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 93, p. 93–108, 2001. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/206. Acesso em: 15 dec. 2025.