Done, G. C., K. L. Bondar, and P. U. Chopade. “Existence and Uniqueness of Solution of Summation-Difference Equation of Finite Delay in Cone Metric Space”. Communications in Mathematics and Applications, vol. 11, no. 3, Sept. 2020, pp. 325-34, doi:10.26713/cma.v11i3.1395.