Tomislav V. Kovandzic, Mark E. Schaffer, Lynne M. Vieraitis, Erin A. Orrick, Alex R. Piquero,
Police, Crime and the Problem of Weak Instruments: Revisiting the “More Police, Less Crime” Thesis Journal of Quantitative Criminology. ,vol. 32, pp. 133- 158 ,(2016) ,
10.1007/S10940-015-9257-6