Ferro Ramos, I. «Synoptic Global Tendencies of Solar Background Magnetic Fields at the 19th Cycle». Geofísica Internacional 31, no. 2 (abril 1, 1992): 159–162. Accedido julio 23, 2024. http://revistagi.geofisica.unam.mx/index.php/RGI/article/view/1276.