Stability of gap solitons in the presence of a weak nonlocality in periodic potentialsI.K. Mylonas, A.K. Rossides and V.M. RothosEur. Phys. J. Special Topics, 225 6-7 (2016) 1187-1197DOI: https://doi.org/10.1140/epjst/e2016-02664-1