Long-term modulation of solar radiation observed on the ground of the earth and its correlation with solar activity variations

Libin, I. Ya., Guschina, R. T., Pérez-Peraza, J., Leyva, A. Jaani, A. y Mikalayunene, U. Geomagnetism & Aeronomy 36-5, 667-670 (36-5, 109-114 en la edición Rusa), 1996