Each of these clues is the list of times which occur in sequence in some movie, TV episode, novel or short story featuring time travel. In the order the clues are given, the answers are:
Pastwatch: the Redemption of Christopher Columbus (novel by Orson Scott Card)
Rip Van Winkle (short story by Washington Irving)
(The) Anubis Gates (novel by Tim Powers)
(A) Connecticut Yankee in King Arthur's Court (novel by Mark Twain)
(The) Time Machine (novel by H.G. Wells)
Back to the Future (film)
Groundhog Day (film)
(A) Swiftly Tilting Planet (novel by Madeline L'Engle)
Yesterday Was Monday (short story by Theodore Sturgeon)
Doomsday Book (novel by Connie Willis)
(A) Sound of Thunder (short story by Ray Bradbury)
War Without End (Babylon V episode)
(The) City on the Edge of Forever (Star Trek episode)
Alphabetizing these answers and reading the starred letters spells out "SECRET HISTORY OF THE VIETNAM WAR", which clues the answer, PENTAGON PAPERS.
2006 MIT Mystery Hunt