H. ISMAIL AND AND, T.; Y. SALEH, H.; M. SULAIMAN, B. Characterizing Internal and External Sets. IRAQI JOURNAL OF STATISTICAL SCIENCES, [S. l.], v. 11, n. 2, p. 63–69, 2011. DOI: 10.33899/iqjoss.2011.027865. Disponível em: https://ojs.uomosul.edu.iq/index.php/stats/article/view/29409. Acesso em: 5 sep. 2025.