Article PubMed The Cochrane database of systematic reviews (2014)
Elliott, Julian; Sim, Ida; Thomas, Jessica; Owens, Nancy; Dooley, Gordon; Riis, Jacob; Wallace, Byron; Thomas, James; Noel-Storr, Anna; Rada, Gabriel; Struthers, Caroline; Howe, Tracey; MacLehose, Harriet; Brandt, Linn; Kunnamo, Ilkka; Mavergames, Chris
10.1002/14651858.ED000091