You won't find any of Epicurus's "books", because no full books have been preserved. The information we have on him is gathered from letters and fragments.
You can get this content from various presocratic anthologies and dedicated collections of Epicurus's work. The Epicurus Reader is a good example of a dedicated collection and contains selected works. The Hellenistic Philosophy book in my comment on your original answer is a great anthology if you are interested in reading work by other Greek philosophers from that general time period.
As you might expect, nobody really owns the copyrights for Epicurus' work and you can find his writings freely available online (at places like the links in Michael Dorfman's answer).