Why can’t I download e-book x from publisher y?

Often, e-books can be saved and printed for personal use, teaching and researching.
Some publishers, however, may not permit this. Some allow to download a certain amount of pages, some allow to download a chapter, and some allow downloading the whole document.
Please take care to mind the publisher’s Terms of Usage and Copyright!

Distributing e-books to a third person, both electronically and in printed form, is prohibited.
Downloading complete e-books or large parts of them systematically, particularly through the use of bots, is also prohibited.

Detailed information on e-books can be found in this overview.