1. [1] B. C. Dhage, Generalized metric space and mappings with fixed point, Bull. Calcutta Math. Soc., vol. 84, 1992, 329-336.
2. [2] B. C. Dhage, Generalized metric space and topological structures I, An. Ştiinţ. Univ. Al. I. Cuza Iaşi, Mat., vol. 46, no. 1, 2000, 3-20.
3. [3] N. V. Dung, N. T. Hieu, S. Radenović, Fixed point theorems for monotone maps on partially ordered S - metric spaces, Filomat, vol. 22, 2014, 1875-1892.10.1186/1687-1812-2014-110
4. [4] Z. Mustafa, B. Sims, Some remarks concerning D – metric spaces, Proc. Conf. Fixed Point Theory and Applications, Valencia (Spain), 2003, 189-198.
5. [5] Z. Mustafa, B. Sims, A new approach to generalized metric spaces, J. Nonlinear Convex Anal., vol. 7, 2006, 280-297.