1. Steam distillation methods for determination of ammonium, nitrate and nitrite;Bremmer;Anal. Chim. Acta,1965
2. Nitrate and nitrite in vegetables;Corré,1979
3. Crop production in recirculating nutrient solution according to the principle of regeneration;Nielsen,1984
4. Nitrat in Gemüse;Schwemmer;Gemüse,1990
5. Sla op voedingsfilm; beheersing van het nitratgehalte;Van der Boon;Groenten en Fruit,1986