Van Zele, M. A. y Otto, O. (1993) «Quiet solar geomagnetic variations at observatories in symmetrical latitudes during a minimum of solar activity», Geoacta, 20, pp. 27–35. Disponible en: https://revistas.unlp.edu.ar/geoacta/article/view/13700 (Accedido: 18 julio 2024).