Periodic Solutions For Nonlinear Systems of Multiple Integro-differential Equations that Contain Symmetric Matrices with Impulsive Actions. Iraqi Journal of Science, [S. l.], v. 64, n. 1, p. 304–324, 2023. DOI: 10.24996/ijs.2023.64.1.28. Disponível em: https://ijs.uobaghdad.edu.iq/index.php/eijs/article/view/5592.. Acesso em: 11 apr. 2025.