49ers LB Chris Borland retiring over concussion concerns
Chris Borland retiring out of concern for head injuries
Potential draft replacements for Chris Borland, Patrick Willis
Will any 49ers player retire after 2022 NFL season?
Replacing NaVorro Bowman with Patrick Willis's versatility - Niners Nation
2017 Opponent Scouting Report: Week 5, 49ers Defense, No, Not Everyone Retired. I Think. - Stampede Blue
San Francisco 49ers' Larry Grant makes hard-hitting impression subbing for injured Patrick Willis – The Mercury News
Hanging It Up: Retirement Is the Latest NFL Trend
49ers' Patrick Willis retires 'happy' – The Mercury News
Patrick Willis injury: San Francisco 49ers' linebacker will have season-ending toe surgery, placed on injured reserve - Sports Illustrated
49ers' Chris Borland retiring at 24, wary of head trauma - WINK News
Patrick Willis' retirement shines light on Chris Borland again - ESPN - San Francisco 49ers Blog- ESPN
San Francisco 49ers: Who Will Replace Patrick Willis and Chris Borland?, News, Scores, Highlights, Stats, and Rumors
Patrick Willis retiring after eight seasons with 49ers