DIN SPEC 1109
DIN SPEC 1109 Fertilizers - Extraction of phosphorus soluble in Joulie's alcaline ammonium citrate; German version CEN/TS 15923:2009
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 02/01/2010
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 02/01/2010