On that subject, I think it's also important to back it up (as far as making it not seem cheap goes). Have multiple characters reference the same works; don't just make up a name and use it once. If it's supposed to be famous/intellectual, I've always found it to be wise to ingrain it into the culture of your setting. It also makes the over-all setting seem more real, because a majority of cultures have famous works of literature/authors or historical figures/wars.
Oh, also, forgot to reference that we talked about this topic (sort of) before: