1. Smith, B. et al. Science 246, 1422–1449 (1989).
2. Trafton, L. Icarus 58, 312–324 (1984).
3. Brown, R. H., Johnson, T. V., Goguen, J. D., Schubert, G. & Ross, M. N. Science 251, 1465–1467 (1991).
4. Buratti, B., Goguen, J. D., Gibson, J. & Mosher, J. Icarus 110, 303–314 (1994).
5. Cruikshank, D. P., Stockton, D., Dyck, H. M., Becklin, E. E. & Macy, W. J Icarus 40, 104–114 (1979).