I would strongly suggest that you ensure all of your PDFs have at least one obvious clickable link to bring visitors to the site's homepage.

Since Google will index your PDFs naturally, it's likely that people may land on the PDFs from the SERPS and you want them to be able to find their way to your homepage.

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Jade Burnside, Ahead of the Web
What good is your web site if no one can find it?
SEO & Optimized Web Site Design