Nguyen, Thanh Nghia, and Trung Hieu Nguyen. “The Fixed Point Theorem for Almost Generalized (ψ ,ϕ)- Contractive Mappings in Ordered B -Metric Spaces”. Dong Thap University Journal of Science, no. 14, Aug. 2015, pp. 64-70, doi:10.52714/dthu.14.8.2015.226.