I think is all murkier than some of the posts suggest. E.g., I wrote some of the early Dummies books... and those books which were all about specific computer topics and often used a trademarked product name in the book title. E.g., Quicken for Dummies or QuickBooks for Dummies. Probably you can debate why this was allowed... maybe because it was what the copyright laws call fair use... (we were obviously doing books about Quicken or QuickBooks and commenting. critique-ing, etc., the named trademarked technology... Or maybe it was because the software companies realized that they benefited in a bunch of ways from having books written about their products... Having a Dummies book written about your product was basically a badge of product success. But here's a funny follow-up to this issue. I also wrote a bunch of books for Microsoft Press called Field Guides that (on the book spine) had a small cartoon character wearing a pith helmet who held a sign that said, I think, "field guide." In no way did this copy the Dummies frontcover design (with the blackboard showing the Dummies book cover). But Hungry Minds legal department--Hungry Minds was then the publisher of the Dummies book--wrote a letter to Microsoft Press saying something like that they thought the cartoonish character holding a sign was getting dangerously close to the appearance of the Dummies cover design... and that they would be closing watching. Weird...