Wagner JD, Anthony MS, Cline JM. Soy phytoestrogens: research on benefits and risks. Clin Obstet Gynecol. 2001 Dec;44(4):843-52.
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