 This was the case at the beginning of the 1970s when also computers with high computing capacity were in operation which delivered numerical results for Delbrück scattering amplitudes with sufficient precision.A first observation of Delbrück scattering was achieved in a high-energy, small-angle photon scattering experiment carried out at DESY (Germany) in 1973, where only the imaginary part of the scattering amplitude is of importance.Agreement was obtained with predictions of Cheng Wu  which later were verified by Milstein and Strakhovenko.