RT Article T1 Private security in Europe JF European journal on criminal policy and research VO 1 IS 1 SP 108 OP 111 A1 Waard, Jaap de LA English YR 1993 UL https://krimdok.uni-tuebingen.de/Record/1640356088 K1 Sicherheitsgewerbe K1 Europa K1 Private Sicherheitsdienste