Ion exchange of ammonium in natural and synthesized zeolites.

Wang Y1, Lin F, Pang W.
J Hazard Mater. 2008 Dec 30;160(2-3):371-5. doi: 10.1016/j.jhazmat.2008.03.006. Epub 2008 Mar 18

https://www.ncbi.nlm.nih.gov/pubmed/18417280