COLLECTED BY
Collection: UNPAYWALL-PDF-CRAWL-2018-07
Web archive data from a crawl of open access PDF URLs provided by Unpaywall.
TIMESTAMPS
The Wayback Machine - https://web.archive.org/web/20180726121432/https://cloudfront.escholarship.org/dist/prd/content/qt1dz6x5xf/qt1dz6x5xf.pdf