on real life princesses
on dresses:
4x19: Chuck buys Princess Diana's old dress for Blair.
4x20: Louis buys a dress that looks like Kate Middleton's for Blair.
on books and cars:
5x03: Blair reads Grace Kelly's biography.
5x(?): Blair gets into a car, while being chased by paparazzi, wearing an outfit similar to Princess Diana's.
4x19: Chuck buys Princess Diana's old dress for Blair.
4x20: Louis buys a dress that looks like Kate Middleton's for Blair.
on books and cars:
5x03: Blair reads Grace Kelly's biography.
5x(?): Blair gets into a car, while being chased by paparazzi, wearing an outfit similar to Princess Diana's.