<http://ns.inria.fr/covid19/PMC7407242#body_text>	<http://purl.org/dc/terms/subject>	"Independent cities in the United States" .
<http://ns.inria.fr/covid19/PMC7407242#body_text>	<http://purl.org/dc/terms/subject>	"Smallpox vaccines" .
<http://ns.inria.fr/covid19/PMC7407242#body_text>	<http://purl.org/dc/terms/subject>	"Partial differential equations" .