NFL's Damar Hamlin could have suffered rare heart trauma during tackle, doctors say
Christian Eriksen collapse brings back dark memories for football
Opinion Football Is Deadly, but Not for the Reasons You Think - The New York Times
Damar Hamlin in critical condition after cardiac arrest during game
From competition to catastrophe: Lives lost on the field, ice and track
Serious Brain Trauma Starts Well Before Young Athletes Go Pro
Aspetar Sports Medicine Journal - Sudden death in football
NFL star Damar Hamlin's family thanks fans for support after his collapse - BBC News
NFL has been slow to embrace mental health support for players
Brain disease CTE seen in most football players in large report
Disease Caused by Concussions Led to Football Player's Suicide, Family Says
What is commotio cordis, which NFL player Damar Hamlin says stopped his heart?