For many disciplines the library uses Patron Driven Acquisition, which is a way of saying that we let you order the book. The records of newly published books appear in the catalog. You can recognize them because they do not have a call number as in the example below.
When you click the title, you will see a Request link under the book information. Enter your username when prompted, and fill out the pickup information so the library can get the book to you. Be warned, however, a book requested for purchase may not come in a quickly as a book requested through Interlibrary Loan. If you need the book quickly, use ILL.