1. Caswell, J.L., Clark, D.H., Crawford, D.F. & Green, A.J.: 1975, Austral. J. Phys. Astrophys. Suppl. No.37.
2. Clark, D.H. & Caswell, J.L.: 1976, Mon. Not. R. astr. Soc., 174, p.267.
3. Clarke, J.N., Little, A.G. & Mills, B.Y.: 1976, Austral. J. Phys. Astrophys. Suppl. No.40.
4. Day, G.A., Caswell, J.L. & Cooke, D.J.: 1972, Austral. J. Phys. Astrophys. Suppl. No.25.
5. Goss, W.M. & Shaver, P.A.: 1970, Austral. J. Phys. Astrophy. Suppl. No.14, p.1.