Long-term outcome of a randomized controlled universal prevention trial through a positive parenting program: is it worth the effort?
Child and adolescent psychiatry and mental health (2010) - Comment
pubmed: 20470435  doi: 10.1186/1753-2000-4-14  issn: 1753-2000 

Kurt Hahlweg, Nina Heinrichs, Annett Kuschel, Heike Bertram, Sebastian Naumann