GUL, Rizwan. An Extension of VIKOR Approach for MCDM Using Bipolar Fuzzy Preference δ-Covering Based Bipolar Fuzzy Rough Set Model. Spectrum of Operational Research, [S. l.], v. 2, n. 1, p. 72–91, 2025. DOI: 10.31181/sor21202511. Disponível em: https://www.sor-journal.org/index.php/sor/article/view/11. Acesso em: 21 jun. 2026.