I have seen a french book “Digital Fantasy” (not the title ) 
with 6 pages about Zbrush on 3 works of Glen Southern !
And with absolutly good translation ! And very comprehensive detailed use of Zbrush !
“Création d’univers imaginaires sur ordinateur”. Imaginary Univers creation with Computer !
Very inspiring good illustrated book! http://www.fnac.com/Shelf/article.asp?PRID=1362905&SID=7D985076%2D1747%2DA29B%2D9394%2DCC4CBE32EF81&UID=0f862ea50%2D1b26%2Db67b%2Dda90%2D658579fcbbc9&AID=&Origin=FnacAff&Pe=1&No=1& Fr=0&Mn=1&Ra=-1&To=0
What a long link Not all is under-lined but it’s works fine
It’s a commecrcial link (I don’t make publicity, just information 
The Zbrush family will grow up
Pilou