“…Direct extension of the Riemann-Liouville fractional integro-differentiation operations to the case of many variables, when these operators are applied for each variable or some of them, gives the so-called partial and mixed fractional integrals and derivatives. They are known [1], as well as [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Thus, in [2], using the two-dimensional Laplace transform, a solution of the two-dimensional Abel integral equation was obtained.…”