@article{Heffernan:137201,
      recid = {137201},
      author = {Heffernan, Peter J.},
      title = {Agricultural Letter},
      journal = {Agricultural Letter},
      address = {1990-01-05},
      number = {820-2016-53040},
      series = {1777},
      pages = {4},
      month = {Jan},
      year = {1990},
      url = {http://ageconsearch.umn.edu/record/137201},
      doi = {https://doi.org/10.22004/ag.econ.137201},
}