1. Association ofOfficialAnalyticalChemists, 1992 : Official Methods of Analysis . AOAC, Washington, DC.
2. Multiple Range and Multiple F Tests
3. EMEA , 1999 : Humic Acids and their Sodium Salts, Summary Report. Committee for Veterinary Medicinal Products , TheEuropeanAgencyfortheEvaluationofMedicinalProducts, 1999 , EMEA/MRL/554/99-Final.