@misc{indiciaeb76ce1676f2c,
  title = {Group sequential methods for cluster randomization trials with binary outcomes.},
  author = {Guang Yong Zou and Allan Donner and Neil Klar},
  year = {2005},
  doi = {10.1191/1740774505cn126oa},
  url = {https://pubmed.ncbi.nlm.nih.gov/16422308/},
  note = {Source identifier: 16422308}
}