I found out about it from other avenues but the strategy guide books are available for pre-order. Here are the names of the books available on Amazon as its apparently not so easy to find:
"Tomb Raider Limited Edition Strategy Guide". Costs $24.41. It comes with special digital downloads and some kind of replica item.
The other cheaper guide without digital content is called "Tomb Raider Signature Series Guide". Costs $15.91.