1. Bieging, J., Chapman, B., & Welch, W.J. 1984, ApJ, 285, 256
2. Bieging, J. & Rieu, N.-Q., 1988, ApJ (Letters), 329, L107
3. Bieging, J. & Rieu, N.-Q., 1989, ApJ (Letters), 343, L25
4. Charnley, S.B., Dyson, J.E., Hartquist, T.W., Williams., D.A., 1988a, MNRAS, 231, 169; 1988b, MNRAS, 235, 1257; 1990, MNRAS, 243, 405
5. Danchi, W.C., Bester, M., Degiacomi, C.G. McCullough, P.R., Townes, C.H. 1990, ApJ (Letters), 359, L59