@article{Heffernan:137739,
      recid = {137739},
      author = {Heffernan, Peter J.},
      title = {Agricultural Letter},
      journal = {Agricultural Letter},
      address = {1985-12},
      number = {820-2016-52875},
      series = {1671},
      pages = {4},
      year = {1985},
      url = {http://ageconsearch.umn.edu/record/137739},
      doi = {https://doi.org/10.22004/ag.econ.137739},
}