1. Allen, D.A. and Penston, M.V.: 1974, Nature 251, 110.
2. Blair, G.N., Thaddeus, P. and Davis, J.H.: 1975, preprint.
3. Buhl, D., Snyder, L.E., Lovas, F.J. and Johnson, D.R.: 1974, Astrophys. J. Letters 192, L97.
4. Buhl, D., Snyder, L.E., Lovas, F.J. and Johnson, D.R.: 1975, Astrophys. J. Letters 201, L29.
5. Cahn, J.H.: 1977, Astrophys. J. Letters, in press (15 March).