1. Procedures for testing soils;ASTM,1958
2. Soil Physics;Baver,1956
3. Soil Physics;Baver,1972
4. Particle density;Blake;Methods of Soil Analysis, Part I. Am. Soc. Agron. Monogr.,1965
5. Bulk density;Blake;Methods of Soil Analysis, Part I. Am. Soc. Agron. Monogr.,1965