Left panel: Epeak-Liso ("Yonetoku") correlation for the sample of 92 long GRBs (black symbols) with measured redshifts. The position of short GRBs (red squares) are consistent with this relation. GRBs shown with red stars are long events accordingly to their observed T90 but  they have an intrinsic duration <2 seconds. Right panel: Epeak-Eiso ("Amati") correlation for the same sample of long GRBs (black symbols). Note the inconsistency of short GRBs with the Ep-Eiso correlation defined by long events. Figure adapted from Ghirlanda et al. 2009, A&A, 496, 585.