Close Cusp observations during a sequence of fast IMF $B_z$ reversals,
Cai, H. T., I. W. McCrea, M. W. Dunlop, J. A. Davies, Y. V. Bogdanova, F. Pitout, S. E. Milan, M. Lockwood, S. Y. Ma (2009),
Ann. Geophys., 27 p. 2721–2737,
10.5194/angeo-27-2721-2009.