Team, S. “Common Fixed Point Theorems for Expansive Type Mappings in Cone Heptagonal Metric Spaces: Gizachew Haile, Kidane Koyas, Aynalem Girma”. Thai Journal of Mathematics, vol. 20, no. 2, June 2022, pp. 639–652, https://thaijmath2.in.cmu.ac.th/index.php/thaijmath/article/view/1351.