Stable three generation standard-like model from a tachyonic ten dimensional heterotic-string vacuum Alon E. Faraggi, Viktor G. Matyas and Benjamin Percival Eur. Phys. J. C, 80 4 (2020) 337 Published online: 23 April 2020 DOI: 10.1140/epjc/s10052-020-7894-x