Luo, Zhiguo, and Jianhua Shen. “Oscillation Criteria for Differential Equations With Piecewise Constant Argument”. Tamkang Journal of Mathematics 32, no. 4 (December 31, 2001): 293–304. Accessed April 19, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/344.