Water quality - Determination of free chlorine and total chlorine - Part 2: Colorimetric method using N,N-diethyl-1,4-phenylenediamine, for routine control purposes (ISO 7393-2:1985); German version EN ISO 7393-2:2000— 17 стр.
Methods of soil investigations for agricultural engineering - Chemical laboratory tests - Part 10: Testing and evaluation of water for irrigation— 11 стр.