1. Agra CEAS Consulting for European Commission DG Environment , 2002. Integrated crop management systems in the EU, available from http://ec.europa.eu/environment/agriculture/pdf/icm_finalreport.pdf
2. AOAC (Association of Official Analytical Chemists) , 1995. Official methods of analysis of the Association of Analytical Chemists. Washington DC. USA, 16th edition.
3. Guidelines for collaborative study procedures to validate characteristics of a method of analysis;AOAC (Association of Official Analytical Chemists);Association of Official Analytical Chemists Journal,2005
4. Nitrate accumulation in vegetables and its relationship to quality;Blom‐Zandstra;Annals of Applied Biology,1989
5. CEN (European Committee for Standardisation) , 1998. European standard EN 12014–7. Foodstuffs‐Determination of nitrate and/ore nitrite content – Part 7: Continuous Flow method for the determination of nitrate content of vegetables and vegetable products after Cadmium reduction. Brussels.