E. Bertáné Szabó, S. Berényi, and J. Loch, “The possibility of use of the 0,01 M CaCl2 and Baker- Amacher extractants for the determination of plantavailable potassium”, Acta agrar. Debr., no. 36, pp. 7–15, Nov. 2009, doi: 10.34101/actaagrar/36/2787.