San Francisco 49ers linebacker Chris Borland retires over head injury concerns - ESPN
John Taylor, Patrick Willis are 49ers Hall of Fame inductees
49ers: 5 former players who could come out of retirement to play
49ers, Ravens bring big-hitting defenses to Super Bowl
49ers: Revisiting former San Francisco linebacker Patrick Willis' greatness
49ers boast one of best linebacking corps around - The San Diego Union-Tribune
Ex-NFL player Patrick Willis: What leaving football for Silicon Valley taught me
Report: 49ers lose Patrick Willis for remainder of season - The Globe and Mail
49ers' Patrick Willis will play vs. Eagles (w/video)
49ers' Patrick Willis lost for season (w/video)
Super Bowl XLVII: 49ers' Patrick Willis draws praise from Ravens' Ray Lewis - SB Nation Bay Area
20 September 2010: San Francisco 49ers linebacker Patrick Willis #52 during the NFL regular season game between the New Orleans Saints and the San Francisco 49ers at Candlestick Park in San Francisco