@article{stephen_aneja_2008, title={Trends in agricultural ammonia emissions and ammonium concentrations in precipitation over the Southeast and Midwest United States}, volume={42}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41449098963&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.05.062}, number={14}, journal={Atmospheric Environment}, author={Stephen, K. and Aneja, Viney}, year={2008}, pages={3238–3252} }