Ebook "High Performance Responsive Design" has only 48 pages

I just bought the pre-release ebook of "High Performance Responsive Webdesign" for about 11€. It's ok that it is a raw version, that's what I expected, but the PDF-file contains only 48 pages instead of 250. I think this is a bit short, even for a pre-release book ;)
Could it be that this is a false PDF-file?
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