COLLECTED BY
Collection: MSAG-PDF-CRAWL-2017
Microsoft Academic Graph public corpus (Feb 2016) PDF URLs, filtered to remove large sites (pubmed, citeseerx, arxiv) and already-crawled URLs.
TIMESTAMPS
The Wayback Machine - https://web.archive.org/web/20170809050735/http://www-anw.cs.umass.edu/pubs/1995_96/houk_bb_BBS96.pdf