Patriots' Rob Gronkowski announces his retirement following nine NFL seasons - Los Angeles Times
Gronk's legacy: How does he stack up among the best to ever play tight end? - The Boston Globe
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Rob 'Gronk' Gronkowski announces retirement from Buccaneers, NFL on Instagram
Rob Gronkowski announces retirement
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Rob Gronkowski Announces Retirement
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Former Arizona Wildcat Rob Gronkowski retires from NFL for second time - Arizona Desert Swarm
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