Cita APA (7a ed.)

Clark, X., Hatton, T. J., & Williamson, J. G. (2002). Where do U.S. immigrants come from, and why? National Bureau of Economic Research.

Cita Chicago Style (17a ed.)

Clark, Ximena, T. J. Hatton, y Jeffrey G. Williamson. Where Do U.S. Immigrants Come from, and Why? Cambridge, MA: National Bureau of Economic Research, 2002.

Cita MLA (9a ed.)

Clark, Ximena, et al. Where Do U.S. Immigrants Come from, and Why? National Bureau of Economic Research, 2002.