API MPMS 9.1-1981 石油测量标准手册第 9 章 密度测定第 1 节 密度 相对密度(比重) 或原油和液态石油产品的 API 比重的比重计测试方法(ASTM D1298)(R 1992)
Manual of Petroleum Measurement Standards Chapter 9 - Density Determination Section 1 - Hydrometer Test Method for Density@ Relative Density (Specific Gravity)@ or API Gravity of Crude Petroleum and Liquid Petroleum Products (ASTM D1298)(R 1992)