Investing: 1) The Intelligent Investor - Benjamin Graham 2) Security Analysis - Benjamin Graham 3) Common Stocks and Uncommon Profits - Philip Fisher 4) The Little Book of Common Sense Investing - John Bogle 5) The Most Important Thing - Howard Marks
Economics: 1) An Inquiry into the Nature and Causes of the Wealth of Nations - Adam Smith 2) Where Are the Customers' Yachts: or A Good Hard Look at Wall Street - Fred Schwed 3) stuff by John Maynard Keynes (never heard him mention exact title)
Others: 1) Poor Charlie's Almanac - Charles Munger 2) Business Adventures - John Brooks 3) How to win friends and influence people - Dale Carnegie
Then there are some things I've never heard him explicitly recommend but I think are definitely worth reading: 1) Letter to shareholders (all of them, you can find the ones of his partnership and earlier ones online) 2) The Snowball - Alice Schroeder 3) Tap Dancing to Work - Carol Loomis (There are tons of books on Buffett, but these two are friends of his)
Also, if you ever go to his shareholders meeting, there's a whole list of "Buffett approved books". Some that I can remember from this years meeting (other then the ones mentioned above): 1) all of them found on https://www.poorcharliesalmanack.com/ 2) Dream Big - Cristiane Correa 3) a bunch more that I cant remember
Finally on his investing, he has laid out a bunch of times what he believes is best for ordinary people who aren't going to devote most of their time to investing namely, buy a low cost index fund (he recommends Vanguards, I believe it was this one https://personal.vanguard.com/us/funds/snapshot?FundId=0540&... ) I'm not quite sure why so little people (that I know) listen to him. It seems that people want to show that they can outperform the market, but rarely do.