UMAR, A. Riemann Integral as a Special Case of Riemann-Stieltjes Integral. International Journal of Science for Global Sustainability, [S. l.], v. 6, n. 4, p. 12, 2021. Disponível em: https://mail.fugus-ijsgs.com.ng/index.php/ijsgs/article/view/72. Acesso em: 3 aug. 2026.