Sydney McLaughlin breaks women's 400 metres hurdles world record ahead of Tokyo Olympics - ABC News
400 Metres
400 METER WORLD RECORD || WHO WILL BREAK IT? - YouTube
400 metres hurdles - Wikipedia
Usain Bolt - Wikipedia
200 metres - Wikipedia
The men's 400 world record moves rarely, but it does move dramatically
400 Metres
400 metres at the Olympics - Wikipedia
Sydney McLaughlin breaks women's 400m world record in front of home crowd | Sports | dailyemerald.com
Brilliant Van Niekerk smashes 400m world record | Reuters
4 × 400 metres relay - Wikipedia
Michael Norman puts world record on notice at Mt. SAC relays – Orange County Register
Track's Most Resilient (and Suspect) Record Is in Danger - The New York Times
Tokyo Olympics: New world record by Warholm of Norway in 400m hurdles
Tokyo Olympics: List Of World Records Set | Olympics News
400 metres - Wikipedia
Namibia's Mboma sets world under-20 400m record of 48.54sec in Bydgoszcz
Norway's Warholm breaks 400 metres hurdles world record | Reuters
Dalilah Muhammad Breaks Her Own World Record in the 400-Meter Hurdles - The New York Times
Miller-Uibo still leads world list in 200, 400 metres | The Tribune
Van Niekerk betters 400m world record
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How do lane assignments and starting spots work in track? - SBNation.com
The World Record Suspicion survey, and some related thoughts
List of world records in athletics - Wikipedia
