DIN SPEC 1105
DIN SPEC 1105 Fertilizers - Extraction of soluble phosphorus according to Petermann at ambient temperature; German version CEN/TS 15922:2009
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