1. Barucci, M.A., Capria, M.T., Coradini, A., & Fulchignoni, M., 1987. Preprint.
2. Bender, D.F., 1979. In: Asteroids, ed. Gehrels, T., University of Arizona Press, Tucson.
3. Chapman, C.R., 1987. Preprint.
4. Davies, J.K., 1986. Mon. Not. R. astr. Soc. 221, 19p.
5. Davies, J.K., Green, S.F., Stewart, B.C., Meadows, A.J., Aumann, H.H., 1984. Nature 309, 315.