Finite difference approximation of eigenvibrations of a bar with oscillator D. M. Korosteleva, L. N. Koronova, K. O. Levinskaya and S. I. Solov’ev MATEC Web Conf., 329 (2020) 03030 Published online: 26 November 2020 DOI: 10.1051/matecconf/202032903030