GYLYS, A. Über lineare inhomogene System von Differential-Differenzengleichungen. Lithuanian Mathematical Journal, [S. l.], v. 11, n. 1, p. 77–92, 1971. DOI: 10.15388/LMJ.1971.20962. Disponível em: https://www.journals.vu.lt/LMJ/article/view/20962.. Acesso em: 6 may. 2024.