Youth gangs - a big issue with many theories but poor research / Eurekalert, 15 April 2008
http://www.eurekalert.org/pub_releases/2008-04/w-yg-041108.php
"Youth gangs cause considerable personal and social damage worldwide, yet while there are many theories about how they form and how to prevent young people becoming involved, there is no evidence to back two of the key theories, according to the results of two Cochrane Systematic Reviews.@"