1. AASHTO M 145-91 (2012), 2012. Standard Specification for Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes, AASHTO Standards. AASHTO, Washington, DC.
2. AASHTO T 236, 2018. Standard Method of Test for Direct Shear Test of Soils under Consolidated Drained Conditions. AASHTO, Washington, DC.
3. AASHTO T 296, 2010. Standard Method of Test for Unconsolidated, Undrained Compressive Strength of Cohesive Soils in Triaxial Compression. AASHTO, Washington, DC.
4. Relationship of tire sinkage depth to depth of soil compaction;Adam;Trans. ASAE,1995
5. The san dimas soil core sampler;Andrews;Soil Sci.,1958