@article{ETD,
      school = {Ph.D.},
      author = {Walinsky, Clifford and },
      url = {http://digitalcollections.ohsu.edu/record/246},
      title = {Constructive negation in logic programs},
      publisher = {Oregon Graduate Center},
      number = {ETD},
      doi = {https://doi.org/10.6083/M46H4FCP},
      recid = {246},
      address = {1987},
}