Adewale , O. K., and E. K. Osawaru. “G-Cone Metric Spaces over Banach Algebras and Some Fixed Point Results”. International Journal of Mathematical Sciences and Optimization: Theory and Applications, Vol. 2019, no. 2, Oct. 2019, pp. 546 -57, http://ijmso.unilag.edu.ng/article/view/480.