_:n029ead5c70534ed7a9e90ae5d402c1baxb1
<http://schema.org/isAccessibleForFree>
"true"^^<http://www.w3.org/2001/XMLSchema#boolean>
<https://ccforum.biomedcentral.com/articles/10.1186/s13054-015-0908-7/figures/4>