Non-tachyonic semi-realistic non-supersymmetric heterotic-string vacuaJohar M. Ashfaque, Panos Athanasopoulos, Alon E. Faraggi and Hasan SonmezEur. Phys. J. C, 76 4 (2016) 208DOI: https://doi.org/10.1140/epjc/s10052-016-4056-2