My friend is looking for a book. It is fiction book set in the 80s in Washington Square Park. The main character is recruited by a secret organization that sends people back in time to fix events. He was sent into the past to discover the meaning of a newspaper clipping talking about the end of the world. At the end it he realized the news paper clipping was actually talking about the end of the "World Newspaper building. I know it is a stretch but if anyone has read and remembers what the title of the book is called, it would be much appreciated.

Time and Again by Jack Finney?

I vaguely remember a more young adult type novel with a similar plot, but can't think of the name off the top of my head.

That's it!  Thank you so much!