GB/T 39500-2020.Leather-Physical and mechanical tests-Determination of apparent density and mass per...
GB国家标准
GB国家标准
GB国家标准
GB/T 39500-2020 皮革 物理和机械试验视密度和单位面积质量的测定
GB/T 39500-2020.Leather-Physical and mechanical tests-Determination of apparent density and mass per...