Eck, John E.; Spelman, William (January 1987). "Who ya gonna call? The police as problem-busters". Crime & Delinquency. 33 (1): 31–52. doi:10.1177/0011128787033001003. S2CID145316412.
Eck, John E.; Spelman, William (January 1987). "Who ya gonna call? The police as problem-busters". Crime & Delinquency. 33 (1): 31–52. doi:10.1177/0011128787033001003. S2CID145316412.