Abbas, Mujahid, Vladimir Rakočević, and Zahra Noor. “Perov Multivalued Contraction Pair in Rectangular Cone Metric Spaces”. Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy 8, no. 3 (September 26, 2021): 484–501. Accessed May 18, 2024. https://math-mech-astr-journal.spbu.ru/article/view/11828.