Afraimovich, E. L., Kosogorov, E. A., Leonovich, L. A., Lesyuta, O. S. and Ushakov, I. I. (2002) “GPS detection of the instantaneous response of the global ionosphere to strong magnetic storms with sudden commencement”, Annals of Geophysics, 45(1). doi: 10.4401/ag-3490.