Cita APA (7th ed.)

Gallup, J. L., Sachs, J. D., & Mellinger, A. D. (1998). Geography and economic development. National Bureau of Economic Research.

Cita Chicago (17th ed.)

Gallup, John Luke, Jeffrey D. Sachs, i Andrew D. Mellinger. Geography and Economic Development. Cambridge: National Bureau of Economic Research, 1998.

Cita MLA (9th ed.)

Gallup, John Luke, et al. Geography and Economic Development. National Bureau of Economic Research, 1998.