R. Malekian and  J. Abedi-Koupai and  S. S. Eslamian,  Use of Zeolite and Surfactant Modified Zeolite as Ion Exchangers to Control Nitrate Leaching.   journal   = {International Journal of Geological and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2011, vol. 52(4). 267 - 271
    [viewed 19 September 2020]. Available from: https://publications.waset.org/pdf/12522.