Mažeikienė, A., M. Valentukevičienė, M. Rimeika, A. B. Matuzevičius, and R. Dauknys. “Removal of Nitrates and Ammonium Ions from Water Using Natural Sorbent Zeolite (clinoptilolite)”. Journal of Environmental Engineering and Landscape Management, vol. 16, no. 1, Mar. 2008, pp. 38-44, doi:10.3846/1648-6897.2008.16.38-44.