Start with high-confidence mutual funds & etfs books, then narrow by subgenre or adjacent topics.
How to Invest $50-$5,000 10e
Nancy Dunnan
All About Index Funds
Richard A. Ferri
Skill Versus Luck
Michael A. Ervolini
What Wall Street Doesn't Want You to Know
Larry E. Swedroe
Heads I Win, Tails I Win
Spencer Jakab
Bogle on Mutual Funds
John Bogle
The Morningstar Approach to Investing
Andrew Leckey, Louis Rukeyser
The Right Way to Invest in Mutual Funds
Walter Updegrave
Morningstar Guide to Mutual Funds
Christine Benz
Mutual Fund Industry Handbook
Lee Gremillion
One Up on Wall Street
Peter Lynch
Unconventional Success
David F. Swensen
Your Essential Guide to Sustainable Investing
Larry E. Swedroe, Samuel C. Adams
Bond Investing for Dummies
Russell Wild MBA, Steven Jay Cohen
The Little Book of Common Sense Investing
John C. Bogle
Common Sense on Mutual Funds, Updated 10th Anniversary Edition
John C. Bogle, David F. Swensen