Operator product expansion and quark condensate from lattice QCD in coordinate spaceV. Gimenez, V. Lubicz, F. Mescia, V. Porretti and J. ReyesEur. Phys. J. C, 41 4 (2005) 535-544DOI: https://doi.org/10.1140/epjc/s2005-02250-9