Fig. (1) (Color on line). Scanned insert from Fig. (6) of  showing the scatter plot of the two photon invariant mass M(γ3γ4) (in MeV),
versus the two photon invariant mass M(γ1γ2) (in MeV). The areas surrounded by red squares correspond to the narrow weakly excited
low mass unflavored mesons highlighted in this work. The three blue circled areas correspond to M(γγ) ≈ 743 MeV (see text). Reprinted
figure with permission from Claude Amsler, Reviews of Modern Physics, Vol. 70, 1293 (1998).