Be aware that these are the people who cold call "IT Professionals" and 
ask them to "review" a book, then bill them for an outrageous price as 
an effort to force sell their products.  While the books are allright as 
far as content goes, they rely on the idea that they're being bought 
with company money by people to whom price doesn't matter.  We're 
talking $70 - $90 for paper bound books, worse than the Sams and similar 
manuals, far worse than O'Reilly.