Adam Smith's 1776 book laid the foundation of free-market economics with the idea of the invisible hand. See its key ideas and what it teaches traders.
Trading Foundations
All articles, page 7
A summary of John Bollinger's book: why a band tag is not a signal, what %b and BandWidth measure, the Squeeze, the head fake and his 3 methods.
Security Analysis by Benjamin Graham and David Dodd, first published in 1934, is the founding text of value investing. Its key ideas and how to apply them.
The Intelligent Investor, first published in 1949, teaches value investing: buying a stock for less than it is worth. Its key ideas and how to use them.
Start with Benjamin Graham's The Intelligent Investor, which teaches the ideas the field is built on. Here are 17 finance books with the key idea of each.