"The Campaign in German South West Africa 1914-1915" by Brigadier-General J.J. Collyer C.B., C.M.G., D.S.O. is the book that springs to mind when we think of histories of the war in GSWA.
A work that has probably never seen the light of day for many years is to found here on the website. It is a history of the campaign written in 1915-1916 by Major J.G.W.Leipoldt, D.S.O. a surveying and intelligence officer serving with the South African troops in GSWA. The report was the official report sent by the South African Govt. to the British war office and was without a doubt used by Collyer, although not credited in his book.
The Sections on the Strategic and especially the tactical operations are of great interest and I find the maps to very very, very good.