Butris RN, Faris HS. Periodic Solutions For Nonlinear Systems of Multiple Integro-differential Equations that Contain Symmetric Matrices with Impulsive Actions. Iraqi Journal of Science [Internet]. 2023 Jan. 30 [cited 2026 Jul. 1];64(1):304-2. Available from: https://www.ijs.uobaghdad.edu.iq/index.php/eijs/article/view/5592