Goldberg X, Fatjó-Vilas M, Alemany S, Nenadic I, Gastó C, Fañanás L. Gene–environment interaction on cognition: A twin study of childhood maltreatment and COMT variability. Journal of Psychiatric Research. 2013 Jul;47(7):989–94. doi: 10.1016/j.jpsychires.2013.02.002.