* Clive Cowley, "Journey into Namibia" ([http://www.orusovo.com/guidebook/default.htm])* Basil Davidson (1963), "Old Africa Rediscovered".
* Clive Cowley, "Journey into Namibia" ([http://www.orusovo.com/guidebook/default.htm])* Basil Davidson (1963), "Old Africa Rediscovered".