If you're looking for an e-book that's unavailable in Library Search, you may have other options.
First, check to see if there's a print copy available. From the item's page check under the Get It section. The information in this section will tell you whether there are print copies available, and if so, where you can find them.
If there's no print copy available, you may request a copy via Interlibrary Loan (ILL), and the ILL team will borrow a print copy on your behalf from another library around the world. In rare cases, an electronic copy may be available via ILL, so feel free to include a note indicating your preference for an electronic copy when available.
You may also want to take a look at WorldCat to see if there's a copy of the item in a library nearby. If you're in a hurry, you may be able to get the item more quickly that way.
If you have a membership at a public library, you might check to see if they have the item available for you.