TY  - RPRT
TI  - Adaptive sample size calculations in group sequential trials.
AU  - W Lehmacher
AU  - G Wassmer
PY  - 1999
DO  - 10.1111/j.0006-341x.1999.01286.x
UR  - https://pubmed.ncbi.nlm.nih.gov/11315085/
ID  - 11315085
ER  -