Could you please send me an electronic version of your paper "The packing density in proteins: standard radii and volumes", JMB 290, 1999, p253-266?
Essentially all of my work is available on-line. Go to:
and click on the appropriate "preprint" link. You will be get a preprint or (if appropriate) journal reprint of the paper you want. There should be NO password challenges or other barriers. Usually, the papers are in PDF format but some are in HTML. (Other formats are available directly from http://papers.gersteinlab.org/e-print.)