Biases in the estimation of velocity dispersions and dynamical masses for galaxy clusters A. Ferragamo, J.A. Rubiño-Martín, J. Betancort-Rijo, E. Munari, B. Sartoris and R. Barrena EPJ Web Conf., 228 (2020) 00011 Published online: 27 January 2020 DOI: 10.1051/epjconf/202022800011