Erviö, Raimo, and Osmo Mäkitie. “Studies on the Effect of Clay and Organic Matter Contents on the Determination of Cation Exchange Properties in Clay Soils by the Ammonium Acetate and Methylene-Blue Methods”. Agricultural and Food Science 41, no. 2 (May 1, 1969): 73–81. Accessed May 20, 2024. https://journal.fi/afs/article/view/71727.