For German readers, there is now a biography on Heinrich Schnee available. It was published in 2017.
The Bundesarchiv has an online catalogue of material relevant to the war and Schnee. An English version can be found here.
The casualty list amongst other correspondence regarding the 1914 Battle of Sandfontein .
In case you haven’t yet seen this – a postal history of the war in Africa: GSWA by ASLC Leiden
The Armchair Historian has a 15 minute animated video of the campaigns in Africa. Be warned, there is an irritating promotion for the sponsor of the video (about 30secs) and factual inaccuracies.
There’s an article by an RAMC officer in East Africa (pgs5-8). He travels via Galippoli.
Mel Page has recently published his Chiwaya War Voices through GWAA if you didn’t spot this in last month’s bookshop selection. He has also had an article published comparing African and American farmers and the war.