Farazmand, Ali (1998). „Persian/Iranian Administrative Tradition”. Ур.: Jay M. Shafritz (Editor). International Encyclopedia of Public Policy and Administration. Boulder, CO: Westview Press. стр. 1640––. – Excerpt: "Persians never practiced mass slavery, and in many cases the situations and lives of semi-slaves (prisoners of war) were in fact better than the common citizens of Persia." (pp.) 1642
Burkholder, Mark A.; Johnson, Lyman L. (2019). „1. America, Iberia, and Africa Before the Conquest”. Colonial Latin America (на језику: енглески) (10th изд.). Oxford University Press. стр. 10. „Wealth rested heavily on the possession of slaves across the large empires of West Africa as well as in Benin and other kingdoms […] Slave owners in sub-Saharan Africa also employed their chattel in a variety of occupations.”
Lockhart, James; Schwartz, Stuart (1983). Early Latin America. New York: Cambridge University Press. стр. 138. „The encomienda in its early heyday granted a lifetime monopoly on the utilization of temporary Indian labor in a given area to one Spaniard, the encomendero.”
For sources about the concept of "wage slavery" and its various interpretations, see „wage slave”. dictionary.com. Приступљено 4. 3. 2013.CS1 одржавање: Формат датума (веза)
Alexander, J. (2001). „Islam, Archaeology and Slavery in Africa”. World Archaeology (на језику: енглески). 33 (1): 51. JSTOR00438243. doi:10.1080/00438240120047627. „Chattel-slaves were needed, especially from the ninth to thirteenth centuries, in the gold and emerald (carbuncle) mines of the Wadi Allaqi in the deserts east of the Nile’s 2nd Cataract”
Herzog, Tamar (2018). „Indigenous Reducciones and Spanish Resettlement: Placing Colonial and European History in Dialogue”. Ler História. 72 (72): 9—30. S2CID166023363. doi:10.4000/lerhistoria.3146.
Alexander, J. (2001). „Islam, Archaeology and Slavery in Africa”. World Archaeology (на језику: енглески). 33 (1): 51. JSTOR00438243. doi:10.1080/00438240120047627. „Chattel-slaves were needed, especially from the ninth to thirteenth centuries, in the gold and emerald (carbuncle) mines of the Wadi Allaqi in the deserts east of the Nile’s 2nd Cataract”
Herzog, Tamar (2018). „Indigenous Reducciones and Spanish Resettlement: Placing Colonial and European History in Dialogue”. Ler História. 72 (72): 9—30. S2CID166023363. doi:10.4000/lerhistoria.3146.