OPEN ACCESS REPOSITORIES

Research Papers in Economics - http://repec.org/

Library of Congress - https://www.loc.gov/

HathiTrust Digital Library: https://www.hathitrust.org/

NDL: https://ndl.iitkgp.ac.in/

BASE - https://www.base-search.net/

CORE - https://mla.hcommons.org/core/

OPEN DOAR - https://v2.sherpa.ac.uk/opendoar/

Open Access Directory - http://oad.simmons.edu/oadwiki/Disciplinary_repositories