1. Allen, D.A. & Wickramasinghe, D.T., 1981, Nature
294, 239.
2. Al-Mufti, S., 1994, PhD Thesis, University College, Cardiff.
3. Bowley, J.E., Adamson, A.J. & Whittet, D.C.B., 1999. Mon. Not. Roy. astr. Soc., in press.
4. Crovisier, J. et al: 1997. Science
275, 1904.
5. Gezari, D.Y., Schmitz, M., Pitts, P.S. & Mead, J.M., 1993. Catalogue of Infrared Observations, NASA Reference Publ. 1294.