Housefield, James (2016). Playing with Earth and Sky: Astronomy, Geography, and the Art of Marcel Duchamp. Hanover, New Hampshire: Dartmouth College Press. p. 33. ISBN978-1-61168-957-0. «[...] the Ministry of Education under the leadership of Jules Ferry in the 1870s and '80s.27 In these so-called Ferry maps displaying France and her regions, the mapmaker blackened the territories of Alsace-Lorraine, long contested, and taken from France by Germany in the wake of the Franco-Prussian War of 1870–71.»
Adu Boahen, A. and the International Scientific Committee for the Drafting of a General History of Africa, ed. (2000). General History of Africa(en inglés). Vol. III. Africa Under Colonial Domination 1880-1935. París, Francia: UNESCO Publishing. pp. 223-224. ISBN0-520-03918-1. Consultado el 11 de diciembre de 2013.