Bravo, S., Mendoza, B. y Pérez Enríquez, R. 1991. Geomagnetic storm sudden commencements and their possible sources at the sun. Geofísica Internacional. 30, 1 (ene. 1991), 23–30. DOI:https://doi.org/10.22201/igeof.00167169p.1991.30.1.946.