Michels KB, Rothman KJ. Update on unethical use of placebos in randomised trials. Bioethics. 2003 Apr;17(2):188-204.
Bogerd HP, Wiegand HL, Yang J, Cullen BR. Mutational definition of functional domains within the Rev homolog encoded by human endogenous retrovirus K. J Virol. 2000 Oct;74(20):9353-61.