?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=R&rft.au=Ponsford%2C+R&rft.aulast=Ponsford&rft.date=23+May+2018&rft.volume=4&rft.title=Pilot+and+Feasibility+Studies&rft.atitle=Study+protocol+for+the+optimisation%2C+feasibility+testing+and+pilot+cluster+randomised+trial+of+Positive+Choices%3A+A+school-based+social+marketing+intervention+to+promote+sexual+health%2C+prevent+unintended+teenage+pregnancies+and+address+health+inequalities+in+England&rft.genre=article