Ringing the bell about NFL concussions - The Boston Globe
Calvin Johnson never listed as suffering a concussion but says he had his 'fair share'
Calvin Johnson: Concussions played role in retirement
Calvin Johnson Says 'Of Course' He Hid Concussions from Lions Team Doctors, News, Scores, Highlights, Stats, and Rumors
NFL Concussions: The 2012-13 Season In Review
The Detroit Lions and Calvin Johnson: A broken relationship
Detroit Lions WR Calvin Johnson says he played against Vikings despite concussion
Here's what we learned from the Calvin Johnson interview - Pride Of Detroit
Calvin Johnson: Concussions played role in retirement
Calvin Johnson: They were giving (painkillers) out like candy. : r/nfl
Calvin Johnson: Lions Made Me Change My Story About Concussion
Banged up Chicago Bears in tough against Calvin Johnson, Detroit Lions
Calvin Johnson didn't break his fingers - NBC Sports
NFC North Roundup: Lions rally to beat Eagles 26-23 in OT, Vikings fall to Washington
Concussions And Incompetence: Calvin Johnson Spills Ugly Truths About Lions