@ChrisJWilson @patrickrhone If the author does not have a book page one could link to the search results of a book shopping meta search engine like Bookfinder.com. That is for print books only.

Just taking a brief look, most ebook search engines are for free ebooks so that does not help. I didn't look in depth. I'm not finding one that gives good results from multiple ebook vendors: Amazon, Kobo, Barnes and Noble, etc at the same time. So ebooks are a problem.

I suppose one could create a custom site search from DDG duckduckgo.com/search_bo... that searches Amazon, Kobo, B&N etc and link to the search results. I've not messed with this to see if it would work.