MIKHIN, D. Y. Energy-conserving and reciprocal solutions for higher-order parabolic equations. Canadian Acoustics, [S. l.], v. 27, n. 3, p. 24–25, 1999. Disponível em: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1199. Acesso em: 3 nov. 2024.