Bogle on Index Funds: Why Most Fund Managers Can't Beat the Market
Book: Common Sense on Mutual Funds: Fully Updated 10th Anniversary Edition by John C. Bogle ISBN: 978-0-470-59748-4
This is where the book gets really good. Chapter 5 is about index funds. And if you know anything about John Bogle, you know this is his baby. He literally created the first one.