Violent acts by adolescents in Germany: Data on the quantitive development and distinctions between different types; revised version of a paper presented at the European intensive seminar "Juvenile Aggression and Delinquency" FH Braunschweig/Wolfenbüttel , FB Sozialwesen Braunschweig, March 10-14, 1997 - Böttger, Andreas (Forschungsbericht / KFN, Kriminologisches Forschungsinstitut Niedersachsen e.V., 1997)