Best books on food production in Africa?

I have family members who are currently living in Africa and they have been talking to me about a school /orphanage there that does really good work helping teach the most vulnerable children and adults valuable skills and the locals grow a great deal of their own food.

I'm wanting to send some books on permaculture and food production to donate.

What would be some of the best books to send?

So far, I'm thinking "Sepp Holzer Desert or Paradise" is going to be at the top of the list.  

Are there any books on Zai holes?

Hello Shawn, I was wondering if their location is in a desert or jungle region. Might make a difference upon book recommendations.

I wonder if you could send them good links. The supply is endless,  the price is right, and postage is simple.

The climate of the area is humid sub tropical with a dry season and a wet season. With average temperatures of 80-90F  in the wet season and 40-50f in the dry season.