https://vocabularyserver.com/unesco/en/ UNESCO Thesaurus UNESCO UNESCO 2015-09-16 en 2015-09-18 17:47:15 Tidal energy 2015-09-18 17:47:15 Ocean wave energy https://vocabularyserver.com/unesco/en/xml.php?skosTema=2085https://vocabularyserver.com/unesco/en/xml.php?skosTema=1607https://vocabularyserver.com/unesco/en/xml.php?skosTema=1608