Topological invariants, zero mode edge states and finite size effect for a generalized non-reciprocal Su-Schrieffer-Heeger modelHui Jiang, Rong Lü and Shu ChenEur. Phys. J. B, 93 7 (2020) 125DOI: https://doi.org/10.1140/epjb/e2020-10036-3