Patty, Henry. “HASIL KALI LANGSUNG S-NEAR-RING DAN S-NEAR-RING BEBAS”. BAREKENG: Jurnal Ilmu Matematika dan Terapan 8, no. 2 (December 1, 2014): 1-7. Accessed April 20, 2024. https://ojs3.unpatti.ac.id/index.php/barekeng/article/view/265.