https://w3id.org/framester/conceptnet5/data/en/biologically_harmful_substance <https://w3id.org/framester/conceptnet5/schema/IsA> <https://w3id.org/framester/conceptnet5/data/en/organic_matter> <https://w3id.org/framester/conceptnet5/data/en/biochemically_harmful_substance> risorse dalla linked data cloud