I would like a suggestion about where to start with TBB, my thoughts on this are:
In this condition: from where do I start ?
The first book, though old, will help you get started with TBB, give it a try.
As for the pdf files, I can't find them either. Some time ago (a year or so) they were still available for download and, if I recall correctly, when downloading TBB v 4.1, they were bundled in the package.
If possible, I would like to ask for the pdf files to be available again (when I can't use the web, they're a real life saver :D )
I checked and the only links that are messed up and redirect again to the Downloads page are those for the Code Snippets.
Lastly, you have some code samples and explanations in the User Guide. For example: parallel_for