49ers' Borland Retires, Citing Head-Injury Concerns - WSJ
San Francisco 49ers linebacker Chris Borland retires over head
Chris Borland - Wikipedia
NFL uses Chris Borland retirement as opportunity to tout football
San Francisco 49ers linebacker Chris Borland retires due to health
Chris Borland: NFL player quits over concussion fears - BBC Sport
I retired from the NFL after one season - I was dubbed the most
Expect more early NFL retirements, says former player
How former San Francisco 49ers Chris Borland's retirement could
Chris Borland, 24, says he's leaving the NFL because he fears a
Borland Retirement: Is 24 Too Late to Stop Football Brain Damage?
Borland's Choice: A Harbinger, A Marker, And A Glimpse Of
Ex-49er Borland On Concussion, Brain Damage Fears: 'Too Many