Present day challenges in understanding the geomagnetic hazard to national power grids

- Thompson, A W P, Kotze, P, Ngwira, C M, Lotz, Stefanus I, Gaunt, C T, Cilliers, P, Wild, J A, Opperman, Ben D L, McKinnell, Lee-Anne, Thompson, A W P, Kotze, P, Ngwira, C M, Lotz, S I