Here's my favorite 5:
- Advances in Financial Machine Learning by Marcos Lopez de Prado
- Method in Dealing in Stocks by Joseph Kerr
- How to Make Money in Stocks by William O'Neil
- Evidence-Based Technical Analysis by David Aronson
- Anchored VWAP by Brian Shannon

Knowing how each market interacts with one another does allow you to think out of the box though (ie. stocks to bonds, bonds to currency, currency to commodities, etc). But if you focus solely on one market like I do (and only look at price action on the charts), it shouldn't matter.