TY  - RPRT
TI  - Developments in cluster randomized trials and Statistics in Medicine.
AU  - M J Campbell
AU  - A Donner
AU  - N Klar
PY  - 2007
DO  - 10.1002/sim.2731
UR  - https://pubmed.ncbi.nlm.nih.gov/17136746/
ID  - 17136746
ER  -