S. J. Adebiyi, S. O. Ikubanni, B. O. . Adebesin, B. W. Joshua, and B. J. Adekoya, “Variations of GPS-TEC at an African Low Latitude Station during Geomagnetic Disturbances”, Phys. Memoir, vol. 1, no. 3, pp. 113–125, Sep. 2019.