1. Abgrall, R. & Montagné, J.L., 1989, Rech. Aérosp. 4, 1
2. Abramovici, A. et al., 1995, in Particle and Nuclear Astrophysics and Cosmology in the next Millenium (Proc. of the 1994, Snowmass Summer Study), eds. E.W. Kolb and R. Peccei, World Scientific, Singapore, 398
3. Akujor, C.E., 1992, Astron. Astrophys. 259, L61
4. Anzer, U., Börner, G. & Monaghan, J.J., 1987, Astron. Astrophys. 176, 235
5. Appel, A.W., 1981, Undergraduate thesis, Princeton Univ., Preprint No. 156