Budak, H. “On Refinements of Hermite-Hadamard Type Inequalities for Riemann-Liouville Fractional Integral Operators”. An International Journal of Optimization and Control: Theories & Applications (IJOCTA), vol. 9, no. 1, Jan. 2019, pp. 41-48, doi:10.11121/ijocta.01.2019.00585.