Berger, E., Israel, G., Miller, C., Parkinson, B., Reeves, A., & Williams, N. (2016). World history: Cultures, states, and societies to 1500. History Open Textbooks, 2. https://www.oercommons.org/courses/world-history-cultures-states-and-societies-to-1500/view. CC BY-SA 4.0.
Roe, K. (2012, April 22). Leads castle [Photograph]. Flickr. https://flic.kr/p/c35GPj. CC BY 2.0.
Khan Academy. (2017, January 16). History and prehistory: The origin of humans and human societies [Video file]. https://www.khanacademy.org/humanities/world-history/world-history-beginnings/origin-humans-early-societies/v/history-and-prehistory. CC BY-NC-SA.
Lincoln, A. et al. Human Rights. E-book, MIOpenBook, 2017. OER Commons, http://www.oercommons.org/courses/world-history/view. Accessed 29 January 2019. CC BY-NC-SA 4.0.
Roe, Karen. Leads Castle. 2012 Online image. Flickr, uploaded 29 January 2019, https://flic.kr/p/c35GPj. Accessed 11 May, 2019. CC BY 2.0.
Khan Academy. “History and Prehistory: The Origin of Humans and Human Societies.” YouTube, uploaded by Khan Academy 16 January 2017, https://youtu.be/ObGarwy5Jss. Accessed 11 May 2019. CC BY-NC-SA.