I’m linking the electronic version of the book for those that can’t afford it. However, I recommend buying the book if you can afford it. It comes with a cd that includes some binaural beats that you can use to help you. Mastering Astral Projection
Ironically enough, today I saw a post from Robert Bruce on facebook. If you go to a new site of his, http://astralbob.com/ and sign up for the email list you can download a free, updated ebook version of his rather thorough book, Astraldynamics. I strongly recommend it as a reference.