Photoproduction of Neutral Pions for Incident Photon Energies 400-800 MeV. Search for a Resonant P-11 State and Remarks on the eta Cusp Effect - Bacci, C.; Penso, G.; Salvini, G.; Mencuccini, C.; Reale, A.; Silvestrini, V.; Spinetti, M.; Stella, B. (Phys. Rev., 1967)