Calvin Johnson: NFL players hide concussions often from coaches - Sports Illustrated
Detroit Lions WR Calvin Johnson says he played against Vikings despite concussion
Calvin Johnson says he had a concussion; Lions say no
Mike Freeman's 10-Point Stance: Are Players to Blame for NFL's Concussion Saga?, News, Scores, Highlights, Stats, and Rumors
Calvin Johnson admits that he hid concussions from Lions team doctors
Calvin Johnson Still Furious With Lions, Wants Team To Fork Over $1.6 Mil
Concussions are the most significant problem facing the sport of football, Tuesday Morning Quarterback writes - ESPN
Calvin Johnson: Concussions played role in retirement
Lions receiver calvin johnson 81 hi-res stock photography and images - Alamy
Calvin Johnson: 'You Get Concussed, You Gotta Keep On Playing' - CBS Detroit
Calvin Johnson: Detroit Lions 'wanted me to change my story' about concussions
Calvin Johnson: Detroit Lions WR retires - Sports Illustrated