Marchenko, V.A. 2013. Symmetrically-spectral operators on $\ell_p$ $(1\leq p< \infty)$ and $c_0$ spaces. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics. 1081 (Nov. 2013), 33-44. DOI:https://doi.org/10.26565/2221-5646-2013-1081-04.