Chris Borland paying San Francisco 49ers back 3/4 of his bonus - ESPN
Retiring 49er Chris Borland to pay back NFL signing bonus - Sports Illustrated
San Francisco 49ers linebacker Chris Borland retires over head injury concerns - ESPN
Chris Borland and the Revenge of History
Chris Borland on retirement: The best decision for me - CBS News
Chris Borland to pay back part of signing bonus
Chris Borland - Wikipedia
Luke Kuechly Joins N.F.L.'s Under-30 Retirees Club - The New York Times
Linebacker Chris Borland says he'll repay part of signing bonus to 49ers - MarketWatch
Chris Borland says he's returning most of signing bonus to 49ers