RT Article T1 Gun prevalence, homicide rates and causality: a gmm approach to endogeneity bias JF The Sage handbook of criminological research methods SP 76 OP 92 A1 Kovandzic, Tomislav A2 Schaffer, Mark E. A2 Kleck, Gary 1951- LA English YR 2012 UL https://krimdok.uni-tuebingen.de/Record/1448595452 SN 9781849201759 K1 Schusswaffenbesitz K1 Tötungsdelikte K1 Kausalität