Patrick Willis Says Change 'Must' Happen After 49ers Loss
Patrick Willis Explains Decision to Retire from NFL
49ers Linebacker Patrick Willis, 30, Retiring
Linebacker Patrick Willis Retires - The Source
Linebacker Patrick Willis To Announce Retirement
Lowell Cohn: 49ers defense takes a huge hit
Why would an NFL star retire when he can still play? Patrick Willis explains why he walked away in his prime
Patrick Willis of San Francisco 49ers retires - ESPN
San Francisco 49ers: Who Will Replace Patrick Willis and Chris Borland?, News, Scores, Highlights, Stats, and Rumors
49ers hit hard after unexpected offseason departures - The Boston Globe
Patrick Willis Retired in His Prime, But Where is He Now? - FanBuzz
Bleacher Report - San Francisco 49ers make it official: Patrick Willis will retire. Details