H. Ismail and and, Tahir, Hind Y. Saleh, and Barah M. Sulaiman. “Characterizing Internal and External Sets”. IRAQI JOURNAL OF STATISTICAL SCIENCES 11, no. 2 (June 25, 2025): 63–69. Accessed August 5, 2025. https://rjps.uomosul.edu.iq/index.php/stats/article/view/20914.