@article{Kholkin2014spectrum, author={Kholkin, A..}, title={Spectrum of a non -self-adjoint differential operators with block-triangular matrix coefficients}, journal={Actual directions of scientific researches of the XXI century: theory and practice}, publisher={FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov}, year={2014}, pages={360-364}, volume={2}, issue={4}, }