*''SEO in Practice'' by Dan Richmond. TOP10WARE Corp. (June 2, 2013)
*''SEO in Practice'' by Dan Richmond. TOP10WARE Corp. (June 2, 2013)
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*''The Art of SEO: Mastering Search Engine Optimization (Theory in Practice)'' by Eric Enge, Stephan Spencer, Rand Fishkin, Jessie C. Stricchiola and John Battelle. O'Reilly Media; 1st edition (October 28, 2009)