S. Yahya Mohamed, and P. Umamaheswari. “Vague Positive Implicative Filter of BL- Algebras”. Malaya Journal of Matematik 8, no. 01 (January 1, 2020): 166–170. Accessed November 24, 2024. https://www.malayajournal.org/index.php/mjm/article/view/1362.