Cita APA (7th ed.)

Hatton, T. J., & Williamson, J. G. (2001). Demographic and economic pressure on emigration out of Africa. National Bureau of Economic Research.

Cita Chicago (17th ed.)

Hatton, Timothy J., i Jeffrey G. Williamson. Demographic and Economic Pressure on Emigration Out of Africa. Cambridge, Mass: National Bureau of Economic Research, 2001.

Cita MLA (9th ed.)

Hatton, Timothy J., i Jeffrey G. Williamson. Demographic and Economic Pressure on Emigration Out of Africa. National Bureau of Economic Research, 2001.