TY  - RPRT
TI  - Efficient group sequential designs when there are several effect sizes under consideration.
AU  - Christopher Jennison
AU  - Bruce W Turnbull
PY  - 2006
DO  - 10.1002/sim.2251
UR  - https://pubmed.ncbi.nlm.nih.gov/16220524/
ID  - 16220524
ER  -