The effectiveness and cost-effectiveness of a mindfulness training programme in schools compared with normal school provision (MYRIAD): study protocol for a randomised controlled trial. - Kuyken, Willem; Nuthall, Elizabeth; Byford, Sarah; Crane, Catherine; Dalgleish, Tim; Ford, Tamsin; Greenberg, Mark T.; Ukoumunne, Obioha C.; Viner, Russell M.; Williams, J. Mark G.; MYRIAD team (Trials, 2017)