NENIŠKYTĖ, E. Ober eine Klasse der partiellen Differentialgleichungen. Lithuanian Mathematical Journal, [S. l.], v. 10, n. 1, p. 121–134, 1970. DOI: 10.15388/LMJ.1970.20840. Disponível em: https://www.journals.vu.lt/LMJ/article/view/20840.. Acesso em: 6 may. 2024.