1991YB/T 4004-1991 High-quality magnesia chemical analysis method diantipyrine methane spectrophotometric determination of titanium dioxide content
YB/T 4004-1991 High-quality magnesia chemical analysis method diantipyrine methane spectrophotometric determination of titanium dioxide content was changed to GB/T 5069-2007 Chemical analysis of magnesia-alumina refractories.