1. Allen, D.A. and Cragg, T.A.: 1983,Mon. Not. R. astr. Soc. 203, 777.
2. Bouchet, P., Manfroid, J. and Schmider, F.X.: 1991,Astr. Astrophys. Suppl. 91, 409
3. Carter, B.S.: 1984,MSc Thesis, University of Cape Town.
4. Carter, B.S.: 1990,Mon. Not. R. astr. Soc. 242, 1.
5. Carter, B.S.: 1993, inPrecision Photometry D. Kilkenny, J.W. Menzies and E. Lastovica, eds. SAAO publication, p.100.