1. Ake, T.B., and Johnson, H.R. (1988) Ap.J.
327, 214
2. Bailyn, C.A. (1984) Unpublished M.Sc. thesis, Univ. of Cambridge
3. Balona, L.A. (1987) South African Astr. Obs. Circ
11, 1
4. Bath, G.T. (1975) M.N.R.A.S.
171, 311
5. Batten, A.H., Fletcher, J.M. and Mann, P.J. (1976) P.D.A.O.
15, 121