Gibbons, L., Crane, P. K., Mehta, K. M., Pedraza, O., Tang, Y., Manly, J. J., Narasimhalu, K., Teresi, J., Jones, R. N. and Mungas, D. (2011) “Multiple, correlated covariates associated with differential item functioning (DIF): Accounting for language DIF when education levels differ across languages”, Ageing Research, 2(1), p. e4. doi: 10.4081/ar.2011.e4.