Amory, DE., & Dufey, J. (1984). Adsorption and Exchange of Ca-ion, Mg-ion and K-ion On the Root Cell-walls of Clover and Rye-grass. Plant and Soil : international journal on plant-soil relationships, 80(2), 181-190. https://doi.org/10.1007/BF02161174 (Original work published 1984)