Harvey J.W., F. Hill, R.P. Hubbard, J.R. Kennedy, J.W. Leibacher, J.A. Pintar, P.A. Gilman, R.W. Noyes, A.M. Title, J. Toomre, and R.K. Ulrich, Science272, 1284-1286(1996).
Hill F., G. Fischer, S. Forgach, J. Grier, J.W. Leibacher, H.P. Jones, P.B. Jones, R. Kupke, R.T. Stebbins, D.W. Clay, and R.E.L. Ingram, Solar Physics152, 351-379(1994).