Dhage, Bapurao Chandrabahan. “Approximation Methods in the Theory of Hybrid Differential Equations With Linear Perturbations of Second Type”. Tamkang Journal of Mathematics 45, no. 1 (March 23, 2014): 39–61. Accessed April 25, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/1328.