Cita APA (7th ed.)

Grogger, J., & Willis, M. (1998). The introduction of crack cocaine: And the rise in urban crime rates. National Bureau of Economic Research.

Cita Chicago (17th ed.)

Grogger, Jeff, i Mike Willis. The Introduction of Crack Cocaine: And the Rise in Urban Crime Rates. Cambridge: National Bureau of Economic Research, 1998.

Cita MLA (9th ed.)

Grogger, Jeff, i Mike Willis. The Introduction of Crack Cocaine: And the Rise in Urban Crime Rates. National Bureau of Economic Research, 1998.