The following journal articles and books are useful if you want to learn more about the design or critical appraisal of randomised controlled trials.
Randomised controlled trials
Schulz KF, Grimes DA. Allocation concealment in randomised trials: defending against deciphering. Lancet 2002 Feb 16;359(9306):614-8
Schulz KF, Grimes DA. Generation of allocation sequences in randomised trials: chance, not choice. Lancet 2002 Feb 9;359(9305):515-9
Schulz KF, Grimes DA. Multiplicity in randomised trials II: subgroup and interim analyses. Lancet 2005 May 7;365(9471):1657-61
Schulz KF, Grimes DA. Multiplicity in randomised trials I: endpoints and treatments. Lancet 2005 Apr 30;365(9470):1591-5.
Sample size in RCTs
Schulz KF, Grimes DA. Unequal group sizes in randomised trials: guarding against guessing. Lancet 2002 Mar 16;359(9310):966-70
Schulz KF, Grimes DA. Sample size slippages in randomised trials: exclusions and the lost and wayward. Lancet 2002 Mar 2;359(9308):781-5
Schulz KF, Grimes DA. Sample size calculations in randomised trials: mandatory and mystical. Lancet 2005 Apr 9;365(9467):1348-53