1. The Pierre Auger Cosmic Ray Observatory
2. The surface detector array of the Telescope Array experiment
3. End to the Cosmic-Ray Spectrum?
4. G. T. Zatsepin and V. A. Kuzmin, JETP Lett. 4, 78–80 (1966),
5. [G. T. Zatsepin and V. A. Kuzmin Pisma Zh. Eksp. Teor. Fiz.4,114 (1966)].