Visit this page from your iOS device using Safari and select the book you would like to load into your iBooks.

Student eBook Library

Do you want to read these iBooks on your Mac desktop computer? You can try using an eReader program such as Kitabu.

EPUB files can be opened in most eBook readers, like the B&N Nook and Sony Reader. EPUB files have to be converted before they're usable on the Amazon Kindle (see How To Convert an EPUB File).

EPUB files can also be opened on a Windows computer with various free programs including Calibre, Adobe Digital Editions, Stanza Desktop, Mobipocket Reader Desktop, Okular, and many more.