@misc{indiciaeec34b7f0493a,
  title = {Cigarette smoking, air pollution, and immunity: a model system.},
  author = {A Nulsen and P G Holt and D Keast},
  year = {1974},
  doi = {10.1128/iai.10.6.1226-1229.1974},
  url = {https://pubmed.ncbi.nlm.nih.gov/4611921/},
  note = {Source identifier: 4611921}
}