Twisted mass quarks and the phase structure of lattice QCDF. Farchioni, R. Frezzotti, K. Jansen, I. Montvay, G. C. Rossi, E. Scholz, A. Shindler, N. Ukita, C. Urbach and I. WetzorkeEur. Phys. J. C, 39 4 (2005) 421-433DOI: https://doi.org/10.1140/epjc/s2004-02078-9