@misc{indiciaec8f015d12439,
  title = {Sample size formulae for intervention studies with the cluster as unit of randomization.},
  author = {F Y Hsieh},
  year = {1988},
  doi = {10.1002/sim.4780071113},
  url = {https://pubmed.ncbi.nlm.nih.gov/3201045/},
  note = {Source identifier: 3201045}
}