Hung, Tran Loc. “On Chi-Square Type Distributions With Geometric Degrees of Freedom in Relation to Geometric Sums”. Science and Technology Development Journal 22, no. 1 (March 31, 2019): 180-184. Accessed March 29, 2024. http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/1053.