Chris Borland Retires at Age 24 Over Concussions
Experiment With Former NFL Players Led to New Training for College Athletes
San Francisco 49ers rookie LB Chris Borland retires at age 24 over head trauma concerns – New York Daily News
San Francisco 49ers Chris Borland retires over repeated head trauma
24-year-old NFL player quits over concussion worries
Chris Borland Archives - Jeffrey Sterling, MD
NFL Players Describe Fear, Suicidal Thoughts As Former Teammates Die - Sports Illustrated
Steddy Ambition Guiding Bailey's Return
Chris Borland: NFL player quits over concussion fears - BBC Sport
49ers' Chris Borland, 24, retires because of brain injury concerns - Los Angeles Times