@misc{indiciaee38cf3af39c3,
  title = {Toward development of a projective set.},
  author = {D J Ludwig},
  year = {1972},
  doi = {10.1080/00223891.1972.10119812},
  url = {https://pubmed.ncbi.nlm.nih.gov/4566632/},
  note = {Source identifier: 4566632}
}