Shimhanda, S. ., P. . Cilliers, and S. . Francis. “Analysis of Ionospheric Total Electron Content Variability Determined from Global Navigation Satellite System Data”. Namibian Journal for Research, Science and Technology, vol. 1, no. 1, Oct. 2018, pp. 3-9, doi:10.54421/njrst.v1i1.4.