1. AACC 1983a Approved Methods of the AACC (8th edn). Method No 54.21, American Association of Cereal Chemists, St Paul, MN.
2. AACC 1983b Approved Methods of the AACC (8th edn). Method No 76.30A, American Association of Cereal Chemists, St Paul, MN.
3. AACC 1983c Approved Methods of the AACC (8th edn). Method No 80.60, American Association of Cereal Chemists, St Paul, MN.
4. 1986 Bivariate regression and correlation methods. Report No WRI 86/101, Wheat Research Institute, Christchurch.
5. 1982 Statistical Procedures for Engineering, Management and Science. McGraw-Hill, Tokyo, p 243.