PMC:7029610 / 899-917
Annnotations
LitCovid-sentences
{"project":"LitCovid-sentences","denotations":[{"id":"T8","span":{"begin":0,"end":18},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"The main challenge"}