C. Bücher: _Industrial Evolution_ (tr. by Wickett), New York, 1904.

*Franz Boas: "The Real Race Problem" (_The Crisis_, December, 1910).

---- _Commencement Address_ (Atlanta University Leaflet, No. 19).

*F. Ratzel: _The History of Mankind_ (tr. by Butler), 3 vols., 1904.