At only 64 pages and with large print, this short book is classified as ‘history – juvenile literature’ and takes half an hour to read. Being produced in the US, I thought the publisher might have some evangelical missionary agenda, like the Joshua Project. In fact Rosen is a publisher of under-12 educational material and this title is part of their Heritage Library of African Studies, from Akamba to Zulu.
As for the book, you feel that the content is rather superficial and fragmentary and may well have been shortened or edited into its current slim form. The author has written longer books on the same subject in French, but then so have many others in that language. Not surprisingly, many of the customs described bear close resemblance to the better studied Moors or Tuareg with whom the Tubu share many characteristics.
What one would wish to know is what makes them different other than their fierce reputation. If anything, the wiki-like details presented on the Joshua page are more gritty and pertinent because the fact remains the Tubu, who are said to have adopted Islam less than a couple of centuries ago, remain the least known of the Saharan tribes.