Q. Why do articles appear in my results list even though I chose "Books" on the library's homepage?

It's common for filters to be cleared/reset when you execute a new search. In other words, by changing the search terms in the search box and searching again, the filter is reset.

You can reapply the Books filter on the left side of the screen within the search results. To keep them from resetting during your search session, you can also select "Retain Filters" near the top, under the "Advanced search" link.