PACHPATTE, B. G. “INEQUALITIES RELATED TO A CERTAIN INEQUALITY USED IN THE THEORY OF DIFFERENTIAL EQUATIONS”. Tamkang Journal of Mathematics 29, no. 1 (March 1, 1998): 1–11. Accessed July 15, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4240.