9 11
From Tardis Wiki, the free Doctor Who reference
The terrorist attack that destroyed the World Trade Center on 11 September 2001 became known as 9/11. (PROSE: I Was a Monster!!!, The Danger Men)
Mark Whitaker was a man from 2011 sent back in time to 1994 by the Weeping Angels. In 2003, he said to the Eleventh Doctor: (PROSE: Touched by an Angel)
How do you think I felt on September the 11th, watching all those people die? But I did nothing.
In 2005, Emily Chaudhry and Francis Currie remembered the 11 September attacks; the media wondered if the attacks were due to British involvement in Iraq. (AUDIO: The Longest Night)