Bases from eigenfunctions subsets of two discontinuous differential operators

The work is devoted to the study of basic properties of exponent systems with the degenerate coefficients, special types of which are the combination of eigenfunctions subsets of two discontinuous differential operators. Necessary and sufficient condition of completeness and minimality was assigned, and under certain conditions on the coefficients the basis property of these systems in $L_p$ was proved (Riss basis in $L_2$).