  In this paper presents the results obtained in the field of spectral theory operators of fractional differentiation. Proven a number of propositions which represents independent interest in the theory of fractional calculus. Introduced construction of multidimensional fractional integral in the direction. Formulated the sufficient conditions of representability functions by the fractional integral in the direction, in particular proved the embedding of a Sobolev space in classes of functions representable by the fractional integral in direction. Note that the technique of proof borrowed from the one-dimensional case is of particular interest. It should be noted that was constructed extension of Kipriyanov operator, was found a conjugate operator. This is all creates a complete picture reflecting the qualitative properties of fractional differential operators. 
Spectral Properties of Fractional Differentiation Operators