1 H.J.G.L.M. Lamers, T.P. Snow, C.. de Jager, and A.. Langerwerf, The Astrophysical Journal 325, (1988).
1 H.. Nieuwenhuijzen, C.. de Jager, M.. Cuntz, A.. Lobel, and L.. Achmad, Astronomy and Astrophysics 280, (1993).