Maria, I use all sources you mentioned to obtain books. I have found some overlap, but it has been worth it. I found the same books about Asperger's Syndrome on both sites, and I found the multiplicity of formats very helpful. I could sit on the bus and read the NLS DTB on my Stream, and I could consult the Braille file later on my PAC Mate if I wanted correct spelling of terminology. This is great! Good luck! Kasondra Payne