1. US Food and Drug Administration.https://www.fda.gov/regulatory‐information/search‐fda‐guidance‐documents/clinical‐trials‐guidance‐documents.
2. European Medicines Agency.https://www.ema.europa.eu/en/human‐regulatory/research‐development/clinical‐trials‐human‐medicines.
3. Cross‐over Trials In Clinical Research
4. Prevention of neural tube defects: results of the MRC vitamin study;MRC Vitamin Study Research Group;Lancet,1991
5. Adaptive designs in clinical trials: why use them, and how to run and report them