@misc{indiciaea80c4c51768a,
  title = {Impact of population density on immunization programmes.},
  author = {I Arita and J Wickett and F Fenner},
  year = {1986},
  doi = {10.1017/s0022172400066249},
  url = {https://pubmed.ncbi.nlm.nih.gov/3734432/},
  note = {Source identifier: 3734432}
}