//-->
The conditions of the black worker : study project papers Nos. 10, 11, 12+14, 22, 23, 24+25
Thomas, W. H., (1975)
The native problem in South Africa : With a review of the problem in west and west-central Africa
Davis, Alexander, (1969)
Kamerun unter deutscher Kolonialherrschaft ; Bd. 1
Stoecker, Helmuth, (1960)