Liang, J., Donovan, E., Liu, W., Jackel, B., Spanswick, E., Syrjaesuo, M., Partamies, N., Voronkov, I., Connors, M., Mende, S., Angelopoulos, V., Frey, H., Ge, Y., Russell, C., Rae, J., & Mann, I. (2007). Azimuthal evolution of the aurora in tens of seconds around the expansive phase onset.