restrictions on books

The customs officers in Dammam (not immigration, incidentally, they check passports) may or may not decide to open luggage. If they do open stuff it could be anything from a cursory glance to a thorough examination. I've not known them to look at more than the cover on a book but there's no guarantee they might not open a book and look through it if they thought it necessary.

There are restrictions on books other than "the obvious" - Salman Rushdie novels are not very popular, for instance. I can't imagine any problems with economics books but there can be a fine line between philosophy and religion so you could possibly be on shakier ground there, depending on the exact nature of the book(s).