https://vocabularyserver.com/ivoat/ IVOAT Thesaurus IVOAT astronomy, science, physics IVOAT 2001-05-23 en 2009-11-21 09:39:37 yttrium 2009-11-21 09:39:37 Y https://vocabularyserver.com/ivoat/xml.php?skosTema=1200https://vocabularyserver.com/ivoat/xml.php?skosTema=2819