To search Google for book reviews, there are a few strategies that can be used. (For more information on Google search, please visit the guide on using Google for research.) They rely on the use of quotation marks (to search as a phrase) and the inurl: operator.
The inurl: operator does exactly what it sounds like — it identifies web sites based on the presence of a string of characters in a URL. If you search for inurl:review, it will pull any web site that has the string "review" in it, like this one: https://www.kirkusreviews.com/book-reviews/anthony-aguirre/cosmological-koans/
You can also subtract web sites like Amazon from the results by using a -inurl:amazon. Amazon ranks very highly in the search results because it's an ecommerce site, which is great when you want Amazon reviews, but less effective when you are searching for newspaper, blog, and magazine reviews. The reason one uses inurl: instead of the site: operator is that Amazon has many versions of its web site, and this will catch all of them.
The screen shots below show what these searches look like in practice.