IL'KIV, V. S.; PTASHNIK, B. I. Representation and investigation of solutions of a nonlocal boundary-value problem for a system of partial differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 2, p. 184–194, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5346. Acesso em: 11 apr. 2025.