Garcia-Esteve L, Navarro P, Ascaso C, Torres A, Aguado J, Gelabert E, Martin-Santos R. Family caregiver role and premenstrual syndrome as associated factors for postnatal depression. Arch Womens Ment Health. 2008 Jul;11(3):193-200.
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