1. Balick, B., Frank, A. 2002 Annu. Review Astron. & Astrophys. 40, 439
2. Bains, I., Redman, M.P., Bryce, M., Meaburn, J. 2004 MNRAS 354, 549
3. Bains, I., Bryce, M. 1997 Acta Cosmologica 23, 107
4. Barral, J.F., Cantó, J.F. 1981 Rev. Mex. A & A 5, 101
5. Borkowski, K.J., Harrington, J.P., Tsvetanov, Z.I. 1995 ApJ 449, L143