Photoproduction of neutral pions on hydrogen at photon energies between 200 and 440 mev - Fischer, G.; Fischer, H.; Von Holtey, G.; Kaempgen, H.; Knop, G.; Schulz, P.; Wessels, H.; Braunschweig, W.; Genzel, H.; Wedemeyer, R. (Nucl. Phys. B, 1970)