Kenneth F Schulz, David A Grimes, Douglas G Altman, Richard J Hayes
Schulz K F, Grimes D A, Altman D G, Hayes R J.
Blinding and exclusions after allocation in randomised controlled trials: survey of published parallel group trials in obstetrics and gynaecology
BMJ 1996; 312 :742
doi:10.1136/bmj.312.7033.742