@misc{indiciaec332cfcf01e9,
  title = {A shadow concept.},
  author = {Fred Busch},
  year = {2006},
  doi = {10.1516/f8m4-trm7-xnrp-9ba6},
  url = {https://pubmed.ncbi.nlm.nih.gov/17130078/},
  note = {Source identifier: 17130078}
}