PolitiFact: A short history of the national anthem, protests and the NFL
Colin Kaepernick: What to Know About Quarterback's Protests
National anthem protests: NFL owners consider new rule - Sports Illustrated
The Kaepernick Effect: Protests, Across the NFL and Beyond, in Response to Trump - The Atlantic
How high school football coaches plan to handle national anthem protests
NFL owners say players must stand for the National Anthem
NFL National Anthem Policy, Owners, Roger Goodell - Sports Illustrated
Good Question: What are the NFL rules about the national anthem?
PHOTOS: NFL Players kneel in protest during the National Anthem
Colin Kaepernick's Protest Going Mainstream Was Its Demise