Techie Mania has an interesting list of what it judges to be the top 100 SEO books. WSO Secrets came in at #20 on the list, even though 1/2 of the book is devoted to SEO, the other half is devoted to performance. Google has made speed a ranking factor in SEO rankings, so the two areas are now interrelated.
“Learning SEO will not be a hard task if we have the right tools and resources. Although there are many people who claim that they have the right resources and tools which will help us in understanding and learning SEO, only few of them will really do. Here is a unique list of top 100 SEO books which will really help you to understand what does “SEO” mean and how to learn the process of search engine optimization.”
More info at:
http://www.techiemania.com/the-top-100-seo-books.html