[13] "The Antiquity of Man" by Arthur Keith, M.D.
[14] "The Growth of the Brain" by H.H. Donaldson.
[15] "Social Environment and Moral Progress" by Alfred Russell Wallace, O.M., D.C.L., Oxon.
[16] "The Varieties of Human Speech" by Edward Sapier, in Smithsonian Institute Report for 1912.
[17] "730 Sechuana Proverbs" by Solomon T. Plaatje.
[18] "Throwing the Bones" is the usual form of divination practised by the Natives in Rhodesia.
[19] "What is Civilisation." Article by Professor W.M. Flinders Petrie, in the Contemporary Review for January, 1921.
[20] "The Prince" by Niccolo Machiavelli.
[21] "Children of the Slaves" by Stephen Graham.
[22] Der Christliche Pilger of 9th May, 1920, and Volklinger Nachrichten of 14th June, 1920.