This book, said to be the first on this topic, is published by Justin Kerrod in South Africa. I will try and get a copy for review, but it sounds useful.
ISBN 9780 620 46059 0 www.kerrodantiques.co.za
About the author: Justin & Shire Kerrod have been trading in Antiques & collectibles from the early 90's. With special interest in Mid Century modern design, early ceramics and South African Studio pottery.