How do you correctly number centuries in history?

Timothy Snyder, "On Tyranny: Twenty Lessons From The 20th Century"

The Twentieth Century - Official Trailer - Oscilloscope Laboratories HD

The Twentieth Century in History

Top Artists of the Twentieth Century: A Primer

The 20th Century History in 15 minutes

A Brief History of 20th Century Classical Music (Tetris-style)

The Men Who Dominated The World | Titans Of The 20th Century | Timeline

The Early logos of 20th Century Spongebob (Before 1935)

A Brief Overview of 20th Century Music

Twentieth Century

Why was the twentieth century called the ‘Era of the Book’? | 12 | THE BOOK THAT SAVED THE EARTH...

On The Twentieth Century - Montage

Who Were The 20th Century's Greatest Inventors? | 101 People Who Made The 20th Century | Progress

STEVE GOODMAN - "The Twentieth Century Is Almost Over"

The Twentieth Century and America’s Evolving Relationship with the World, USH14

Twentieth Century (2011 Remastered)

On Tyranny: Twenty Lessons from the Twentieth Century with Timothy Snyder

WW2 'Brown Babies': A little-known part of British 20th Century history - BBC World Service podcast

20th Century in English Literature