UNE-EN ISO 21079-1
Chemical analysis of refractories containing alumina, zirconia and silica - Refractories containing 5 percent to 45 percent of ZrO₂ (alternative to the X-ray fluorescence method) - Part 1: Apparatus, reagents and dissolution (ISO 21079-1:2008) (Endorsed by AENOR in June of 2008.)