A. Ekert: Quantum cryptography based on Bell’s theorem. In: Phys. Rev. Lett. Band67, 1991, S.661, doi:10.1103/PhysRevLett.67.661.
Artur K. Ekert, John G. Rarity, Paul R. Tapster, G. Massimo Palma: Practical quantum cryptography based on two-photon interferometry. In: Physical Review Letters. Band69, 1992, S.1293, doi:10.1103/PhysRevLett.69.1293.