SSRN Uses DOI for Preprint Articles – SSRN

"SSRN is currently experimenting with assigning Preprint DOIs to selected papers on SSRN.

DOIs are Digital Object Identifiers assigned to each new published paper that appears in any journal. DOIs are permanent IDs that always lead to the same result, making it easy to find, link and cite published articles. DOIs are managed by Crossref, a not-for-profit membership organisation...."