SSRN
The metadata import from SSRN does not work, and the PDF file is not downloaded. For ex. try: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2801385
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However, the PDF is currently not automatically attached. SSRN puts wrong information in the HighWire metatag and quite easily one gets an alert page about "unusual download pattern"...
For ex. in this URL http://www.jstor.org/stable/2555816?origin=crossref&seq=1#page_scan_tab_contents
it's downloaded as a web page element, instead of an article element