Elliot et al. (1984). "Structure of the Uranian rings. I. Square-well model and particle-size constraints" Astron J. 89, 1587-1603. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984AJ.....89.1587E&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
Elliot et al. (1984). "Structure of the Uranian rings. I. Square-well model and particle-size constraints" Astron J. 89, 1587-1603. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984AJ.....89.1587E&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf