PMC:1359071 / 652-654 JSONTXT

{"project":"craft-ca-core-ex-dev","denotations":[{"id":"T511","span":{"begin":1,"end":2},"obj":"SO_EXT:sequence_nullness_or_absence"}],"text":"E−"}

{"project":"craft-sa-dev","denotations":[{"id":"T641","span":{"begin":1,"end":2},"obj":"SYM"}],"text":"E−"}