Back in 2012, in response to the Cost Of Knowledge declaration, Elseviermade all articles in "primary math journals" free to read, distribute and adapt after a four-year rolling window.Today, as David Roberts points out,it seems they have silently withdrawn some of those rights.
Mike Taylor (Mon,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: