Existence and Ulam stability of first order nonsingular impulsive and delay integrodifferential system using a concept of the delayed matrix exponential. Punjab Univ. J. Math. [Internet]. 2024 Jun. 2 [cited 2025 Jun. 28];56(6):252-74. Available from: https://pujm.pu.edu.pk/index.php/pujm/article/view/149