Kermausuor, S., & Nwaeze, E. R. (2018). New Ostrowski and Ostrowski-Gruss type inequalities for double integrals on time scales involving a combination of $\Delta$-integral means. Tamkang Journal of Mathematics, 49(4), 277–289. https://doi.org/10.5556/j.tkjm.49.2018.2632