1. Genesis and hardening of Leterite soils;Alexander;U.S. Dept. Agric Tech. Bull,1962
2. Methods of testing soils for Civil Engineering purposes;B.S.L. B.S. 1377,1990
3. General Specifications Roads and Bridge works;Federal Ministry of Works,1970
4. Strain in crystal detected by X-ray;Gilliot;Nature,1966