Playing with Touchgraph, I have tried to search on Amazon for books about metaheuristics. The results are interesting, as one can see on the following graphs :

This one only shows the books themselves. Note the lot of books not connected in the bottom-left side and the highly connected boks about evolutionary computation. I also find interesting that the machine-learning topic on the top and the connexions with computer programming on the right. It surprises me that my "metaheuristic for hard optimization" book is the only one connected with such topics... maybe because of the case studies.

Check also the network of authors and subjects:

The graphic for authors and publishers (Springer is the biggest, as one can expect):

And finally, all the items on one graph: