Question: National Lampoon's Christmas Vacation is a film that stars an actor known for playing Dr. Leonard Hofstadter in what CBS sitcom?
Sentence (from "National Lampoon's Christmas Vacation"): It is the third installment in National Lampoon's "Vacation" film series, and was written by John Hughes, based on his short story in "National Lampoon" magazine, "Christmas '59".
Relevant evidence: No