KHIRINA, G.; SAVCHENKO, A. The story of three letters. Spiritual relay of the generations. V. N. Karazin – E. I. Koltunovsky – M. F. Sumtsov. V. N. Karazin Kharkiv National University Bulletin ‘History of Ukraine. Ukrainian Studies: Historical and Philosophical Sciences’, v. 35, p. 45-50, 28 Dec. 2022.