1 B.W. Carroll, E.G. Zweibel, C.J. Hansen, P.N. McDermott, M.P. Savedoff, J.H. Thomas, and H.M. Van Horn, The Astrophysical Journal 305, (1986).
1 D.E. Winget, H.M. Van Horn, M.. Tassoul, G.. Fontaine, C.J. Hansen, and B.W. Carroll, The Astrophysical Journal 252, (1982).