“…The number of works on the regularized problem with input data in L 2 is quite abundant. The results of this study can be found in the following documents, attached to the regularization methods: the Tikhonov method, see [14,15], the Fractional Tikhonov method, see [16], the fractional Landweber method, see [17,18], the Quasi Boundary method, see [19], the truncation method, see [20], and their references.…”