Who is Rob Gronkowski and why is he retiring?
Rob Gronkowski Retired. Again. - The New York Times
Rob Gronkowski formally announces NFL retirement for second time - On3
Rob Gronkowski announces retirement, can Tom Brady lure Gronk back to Bucs?, NFL
Buccaneers Tight End Rob Gronkowski Says He Will Retire, Again
Rob Gronkowski retires again, but could make another comeback in 2022 or 2023, agent says (report)
Patriots tight end Rob Gronkowski announces retirement
Rob Gronkowski retires: New England Patriots tight end steps away from NFL – The Denver Post
Rob Gronkowski retires, won't join Tom Brady for 3rd season
Rob Gronkowski announces second retirement from NFL