1. An evaluation of direct simple shear tests on clay;Airey;Géotechnique,1987
2. Stress path tests to measure soil strength parameters for shallow landslips;Atkinson,1985
3. Properties of unsaturated colliery clayfills in North-Western Bohemia;Boháč,2003
4. Soil mechanics;Craig,2002
5. Soil, investigation and testing — determination of shear strength, Part 3: Direct shear test;DIN 18137-3,2002