More players are calling it quits in prime of their careers
NFL safety boss says the league could ban helmets one day - BBC Sport
Borland Retirement: Is 24 Too Late to Stop Football Brain Damage?
Chris Borland - Wikipedia
San Francisco 49ers LB Chris Borland to retire due to safety
Who has been our biggest “what if” player? : r/49ers
Andy Baggot: Chris Borland was great on the field, will be even
Chris Borland retires from NFL at just 24 years old, makes his own
49ers Linebacker Quits After 1 Season, Citing Safety Concerns
Hard Truth On Wisconsin Magazine
Chris Borland, Fearing for Health, Retires From the 49ers. At 24
Vontae Davis of Buffalo Bills Retires During an N.F.L. Game - The
49ers ex-linebacker Chris Borland salutes Pat Tillman