Mamghaderi, H., & P. Masiha, H. "Fixed Point Theorems for Single Valued Mappings Satisfying the Ordered non-Expansive Conditions on Ultrametric and Non-Archimedean Normed Spaces", International Journal of Nonlinear Analysis and Applications, 11, 1, 2020, 1–6. doi: 10.22075/ijnaa.2019.3677