Q. How well do databases cover a topic and how well do books cover the same topic?

Generally, academic articles are very focused on a narrow aspect of a topic. Books cover topics a little more broadly, but since the format is longer, have room for deep analysis. In many cases, an academic book is a scholar's further development of a topic they first covered in an article.

You can find books in Virgo.  You can explore databases for articles in the Research Portal.