ZADOROZHNA, N. M.; PTASHNIK, B. I. Nonlocal boundary-value problem for parabolic equations with variable coefficients. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 47, n. 7, p. 915–921, 1995. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5485. Acesso em: 5 dec. 2025.