Daniel, James Z., Byron-Daniel, J Z, Hickman, Matthew, Macleod, John, Wiles, Nicola, Lingford-Hughes, Anne, Farrell, Michael, Araya, Ricardo, Skapinakis, Petros, Haynes, Jon, Lewis, Glyn, "Is socioeconomic status in early life associated with drug use? A systematic review of the evidence", Drug and Alcohol Review, 2009