APA (7e ed.) Bronvermelding

Speirs, M., & Olsen, O. (1992). Indigenous integrated farming systems in the Sahel. World Bank.

Chicago (17e ed.) Bronvermelding

Speirs, Mike, en Ole Olsen. Indigenous Integrated Farming Systems in the Sahel. Washington, D.C: World Bank, 1992.

MLA (9e ed.) Bronvermelding

Speirs, Mike, en Ole Olsen. Indigenous Integrated Farming Systems in the Sahel. World Bank, 1992.