 Four experiments in the 1970s — by Kasday-Ullman-Wu, Faraci-Gutkowski-Notarigo-Pennisi, Wilson-Lowe-Butt, and Bruno-d’Agostino-Maroni — used photon pairs produced in positronium annihilation instead of cascade photons. Of these, all but that of Faraci et al. gave results in good agreement with the quantum mechanical predictions and in disagreement with Bell’s Inequalities. A discussion of these experiments is given in the review article by Clauser and Shimony (1978), who regard them as less convincing than those using cascade photons, because they rely upon stronger auxiliary assumptions.