One of the most important methods in the theory of special functions of mathematical physics is that of generating integral relations for these functions by the simultaneous separability of the 3-dimensional wave equation in different orthogonal coordinate systems. In the present paper it will be shown that a consequent application of this principle of simultaneous separability to more general partial differential equations and higher dimensions yields various types of integral relations for the solutions of a wide class of ordinary differential equations which especially contains all second-order equations of Fuchsian type.
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