Complex sentence: David Letterman referenced the incident in the opening monologue of his television show, Late Show with David Letterman ", on January 8,2009, in which he stated," A couple of days ago, there were UFO sightings in New Jersey.
Split into simpler sentences: David Letterman referenced the incident in the opening monologue of his television show, "Late Show with David Letterman", on January 8,2009. "" A couple of days ago, there were UFO sightings in New Jersey.