Le, Anh Minh, Thi Thu Nguyen, and Thanh Tra Nguyen. n.d. “Asymptotic Periodic Solutions to a Class of Non-Densely Defined Differential Equations With Infinite Delay”. Hong Duc University Journal of Science, no. 7. Accessed September 3, 2026. https://hdujs.edu.vn/index.php/js/article/view/1013.