RT Article T1 A fragmented force: The evolution of federal law enforcement in the United States, 1870-1900 JF Journal of policy history VO 29 IS 4 SP 640 OP 675 A1 Obert, Jonathan LA English YR 2017 UL https://krimdok.uni-tuebingen.de/Record/1912562057 DO 10.1017/S0898030617000306