TY  - RPRT
TI  - Sample size formulae for intervention studies with the cluster as unit of randomization.
AU  - F Y Hsieh
PY  - 1988
DO  - 10.1002/sim.4780071113
UR  - https://pubmed.ncbi.nlm.nih.gov/3201045/
ID  - 3201045
ER  -