@article{singh2017a,
  title = {A Nitrogen Physical Input-Output Table (PIOT) model for Illinois}
  author = {Singh, Shweta; Compton, Jana E.; Hawkins, Troy R.; Sobota, Daniel J.; Cooter, Ellen J.},
  journal = {Ecological Modelling},
  url = {http://www.sciencedirect.com/science/article/pii/S0304380017302168},
  doi = {10.1016/j.ecolmodel.2017.06.015},
  year = {2017}
}