Bi-layer voter model: modeling intolerant/tolerant positions and bots in opinion dynamicsDidier A. Vega-Oliveros, Helder L. C. Grande, Flavio Iannelli and Federico VazquezEur. Phys. J. Spec. Top., 230 14-15 (2021) 2875-2886DOI: https://doi.org/10.1140/epjs/s11734-021-00151-8