1. American Association of State Highway and Transportation Officials (AASHTO). 2001. Standard Specifications for Transportation Materials and Methods of Sampling and Testing, Part 2, Tests: T99 Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop. T193 The California Bearing Ratio. T180 Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop
2. American Society for Testing and Materials (ASTM). 2006. Vol. 04.08, Soil and Rock (I): D0422 Test Method for Particle-Size Analysis of Soils. D0698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft (600 kN-m/m)). D1556 Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method. D1557 Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft(2,700 kN-m/m)). D1883 Test Method for CBR (California Bearing Ratio) of Laboratory-Compacted Soils. D2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System). D4318 Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.
3. Bolander, P., Marocco, D. and Kennedy, R. 1996.Earth and aggregate surfacing design guide for low volume roads302 Engineering Staff, EM-7170-16 USDA Forest Service
4. Use of OR Systems in the Chilean Forest Industries