I'm trying to research genre popularity I'm particularly interested in personal development and how it gets a stronger demand after a hard time Dale Carnegie's How to Win Friend and Influence People (15 million sold) was released during The Great Depression. Napoleon Hill's book of Think and Grow Rich (30 million sold) was also from that era Normal Peale's The Power of Positive Thinking (40 million sold) came out at the height of the cold war. I'm looking for other things like that. I think many self help books were release after Viet Nam but I'm not sure. Anybody know where I can find out? Is there a genre history of popularity somewhere?