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.
Williams VSL. The "unbiased" anchor: bridging the gap between DIF and item bias. Appl Meas Educ. 1997;10(3):253-67. doi: 10.1207/s15324818ame1003_4