“…when a 0 = 1 and a j = 0, j = 1, 2, 3 were studied in [13], [14]. Later, some generalizations of these problems with conditions of the Dirichlet, Neumann, and Robin types, as well as of the Samarskii-Ionkin type, were studied in [6], [7], [10], [11], [15], [19]. Further, in [3], [4] for a nonlocal Laplace operator with involutively transformed arguments in rectangular domains, problems of the Cauchy and Dirichlet types were studied.…”