TY  - RPRT
TI  - Clinical trials: study design and analysis.
AU  - Y van der Graaf
PY  - 1998
DO  - 10.1016/s0720-048x(97)00159-9
UR  - https://pubmed.ncbi.nlm.nih.gov/9639135/
ID  - 9639135
ER  -