Jelte M. Wicherts, Conor V. Dolana, and Han L.J. van der Maas, A systematic literature review of the average IQ of sub-Saharan Africans, Intelligence, Volume 38, Issue 1, January–February 2010, pp. 1–20, https://dx.doi.org/10.1016/j.intell.2009.05.002 8 Mart 2021 tarihinde Wayback Machine sitesinde arşivlendi.
Jelte M. Wicherts, Conor V. Dolana, and Han L.J. van der Maas, A systematic literature review of the average IQ of sub-Saharan Africans, Intelligence, Volume 38, Issue 1, January–February 2010, pp. 1–20, https://dx.doi.org/10.1016/j.intell.2009.05.002 8 Mart 2021 tarihinde Wayback Machine sitesinde arşivlendi.