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Stephenson, Judith and Allen, Elizabeth and Oakley, Ann and Strange, Vicki (2008) The long-term effects of a peer-led sex education programme (RIPPLE): a cluster randomised trial in schools in England. PLoS Medicine, 5 (11). e-e. ISSN 1549-1277
Oakley, Ann and Strange, Vicki and Toroyan, Tami and Wiggins, Meg and Roberts, I and Stephenson, Judith (2003) Using random allocation to evaluate social interventions: three recent UK examples. Annals of the American Academy of Political and Social Science, 589. pp. 170-189.