Anisotropic Dirac cones in monoatomic hexagonal lattices: a DFT studyA.M. Rojas-Cuervo, K.M. Fonseca-Romero and R.R. Rey-GonzálezEur. Phys. J. B, 87 3 (2014) 67DOI: https://doi.org/10.1140/epjb/e2014-40894-9