Green open access refers to making academic, peer-reviewed research that has been published elsewhere (even subscription/sales venues) available for anyone to read freely on the internet by depositing the work in an institutional or subject repository. A large number of journal publishers allow this. Ideally, this is done without embargo. To protect revenue, however, often a publisher imposes a delay.
Martin Paul Eve (Mon,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: