Παραπομπή APA

Malthus, T. R., & Pullen, J. E. (1989). Principles of political economy.

Παραπομπή Chicago Style

Malthus, T R., και John; Ed Pullen. Principles of Political Economy. Cambridge, CUP, 1989.

Παραπομπή MLA

Malthus, T R., και John; Ed Pullen. Principles of Political Economy. 1989.