E. M. Levich, G. I. Geideman, “Triangulability of groups and rings”, Izv. Vyssh. Uchebn. Zaved. Mat., 1972, no. 3, 41–45
1969
2.
E. M. Levich, G. I. Geideman, “Conjugate endomorphisms of vector spaces”, Sibirsk. Mat. Zh., 10:6 (1969), 1234–1241; Siberian Math. J., 10:6 (1969), 913–917
