The Monuments of the Tataouine Region — various academic surveys of the ksour architecture of the Tunisian south exist in French; worth searching for if you read French and want detail on the individual structures and their history.
Handbook to Life in the Medieval World by Madeleine Pelner Cosman and Linda Gale Jones — covers Berber and North African Islamic civilisation including fortified architecture; provides useful background on the social function of the ksar tradition.
Tunisia by various authors (Lonely Planet, Rough Guide, or Bradt) — a practical travel guide covering the Tataouine region, ksour circuit, and logistics for the south. The Bradt guide to Tunisia has consistently strong coverage of the southern region.
The Illustrated Star Wars Universe by Kevin J. Anderson and Ralph McQuarrie — for the production design and location context behind the Tatooine scenes; useful for understanding why Ksar Hadada and the Tataouine region were chosen as filming locations.