https://w3id.org/framester/conceptnet5/data/en/vacuum_tube <https://w3id.org/framester/conceptnet5/schema/DerivedFrom> <https://w3id.org/framester/conceptnet5/data/en/tube.n> <https://w3id.org/framester/conceptnet5/schema/MadeOf> <https://w3id.org/framester/conceptnet5/data/en/glass> risorse dalla linked data cloud