The oldest e-repository, "focusing on Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance, Statistics, Electrical Engineering and Systems Science, and Economics"
"Open archive of the social sciences, provides a free, non-profit, open access platform for social scientists to upload working papers, preprints, and published papers, with the option to link data and code."
RePec proper encorporates multiple services for academic communication in Economics. Among them is MPRA, a service that allows authors whose school doesn't have a repository to upload their papers. https://mpra.ub.uni-muenchen.de/
The Open Library of the Humanities is not a repository, but a publishing cooperative dedicated to publishing open access journals with no author facing open access author charges.
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