What are the best `SEO` books out there?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Greg Kristan: Search Engine Optimization Secrets by Danny Dover
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  Alexandru Cobuz: Honestly don't really think that you'll find everything in the books, keep an eye on the websites, because SEO keeps changing :)
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  Nick Stuart-Miller: I'd agree with Alexandru. A lot of SEO books are outdated now, even ones published last year. It's reported that Google and major search engines change their ranking algorithms up to 500 times a year.
  
  Check out various SEO blogs, Moz, Majestic SEO and always keep an eye on Google Guidelines. Also, I'd suggest that you wouldn't be an SEO professional from simply reading. Get stuck into it. You'll learn 10x more from experience, trial and error.
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  Roderic Van Binst: Well if you are a complete beginner it still wouldn't hurt to read some books and guides to get started (even the slightly outdated ones, even if its just to have an idea how things used to be). "The art of SEO" is quite a good read. ;The second edition of that book came out last year, yet all the fundamentals mentioned within still matter.
  
  Furthermore, there are loads of online content available, such as the beginner guide from Moz:
  
  http://moz.com/beginners-guide-to-seo
  
  And a good advanced seo guide is:
  
  http://www.quicksprout.com/the-advanced-guide-to-seo/
  
  If you need help on a particular topic either post here or shoot me a message, happy to help.
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  W.E. Jonk: Here are some past suggestions from community members:
  https://plus.google.com/107867312262018306040/posts/LmZ5Zh5at7P
  https://plus.google.com/109010361289787518613/posts/H85n4Wrjkdh
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  John Britsios: SEO is an everflux process. That said books can never be up-to-date.
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  Kelvin Bruce-Smith: Thanks for all you suggestions :-) seems I have a lot to be reading :-)