2019DB21/T 3211-2019 Mechanized Technical Regulations for Soil Fertility Cultivation in Corn Fields
2013DB21/T 2102-2013 Technical Regulations for Layered Propagation of Pingou Hybrids
DB21/T 2102-2013 Technical Regulations for Layered Propagation of Pingou Hybrids was changed to DB21/T 3211-2019 Mechanized Technical Regulations for Soil Fertility Cultivation in Corn Fields.