@book{
      international2008iaea,
      title={Guidelines on Nitrogen Management in Agricultural Systems},
      author={ },
      series={entity},
      number={29 },
      year={2008},
      isbn={ },
      url={/publications/7612/guidelines-on-nitrogen-management-in-agricultural-systems },
      publisher={INTERNATIONAL ATOMIC ENERGY AGENCY },
      address={Vienna}
    }