APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (9th ed.) Citation

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