1. C.F. Williamson, S. Kowalski, F.N. Rad, J. Heisenberg, H. Crannell and J.T. O'Brien, private communication (1983).
2. H. Miessen, G. Luehrs, H. Rothhaas, W. Bertozzi, S. Kowalski, C.F. Williamson, R.S. Hicks, R.A. Lindgren. G.A. Peterson and B.L. Berman, private communication (1983).