https://w3id.org/framester/wn/wn30/instances/word-index_of_refraction <https://w3id.org/framester/wn/wn30/schema/Word> <https://w3id.org/framester/wn/wn30/schema/lexicalForm> index of refraction rdf:type <https://w3id.org/framester/wn/wn30/schema/Word> risorse dalla linked data cloud