Before the Jim Rohn’s of the world there were self-development mentor’s like Dr. Orison Marden. He was there even before Napoleon Hill. His bio and works are all over the web and very impressive. I stumbled upon him while reading another self-help guru, and I can tell you I know where they got their material from – Dr. Orison Marden. You can read his books for free or buy them on Amazon (reprints) via Project Gutenberg and UPenn Online Books Page.
Three books I would read immediately.
I just finished these 3 books and I can tell you they are amazing. The Self Investment book is one of my favorites. I gave it to my son to read and learn from. Every Man a King is worth the read too, and Iron Will is the last one I have read. I sent his books to my Kindle via the Project Gutenberg link.