1. Standard Methods for the Examination of Water and Wastewater;APHA,1985
2. Determination and isotope ratio analysis of different forms of nitrogen in soils: 3. Exchangeable ammonium, nitrate and nitrite by extraction-distillation methods;Bremner,1966
3. Nitrogen-total;Bremner,1982
4. Quantitative reduction and inclusion of plant tissue nitrates in Kjeldahl digestion;Goyal;Agronomy J.,1990
5. Dosage par la méthode Kjeldahl des nitrates contenus dans les et les végétaux;Guiraud;Annales Agronomiques,1977