1. AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS (AASHO) (1970): Standard specification for Highway Materials ands Methods of sampling and Testing, 10 th edition.
2. AMERICAN SOCIETY FOR TESTING AND MATERIALS (1975): Special Procedure for testing soil and rock for engineering purposes, Special Technical Publication, 5th edition 479 p.
3. BELL, F.O. (1973): Climate of Fowler's Gap Station; in lands of Fowlers Gap Station (Mabbutt, J.A. ed.) Fowlers Gap Research Series No. 3, p. 45–63, Univ. of N.S.W.
4. HORTA, J.C. DE O.S. (1980): Calcrete-gypcrete and soil classification in Algeria.Eng. Geol, Vol. 15, p.15–52.
5. STACE, H.C.T., HUBBLE, G.D., BREWER, R., NORTHCOTE, K.M., SLEEMAN, J.R., MULCARY, M.J., and HALLSWORTH, E.G. (1968): A handbook of Australian soils, Rellim, Adelaide, 427 p.