Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

'Highway 61 Revisited' and 'Blood On The Tracks' were both albums released by which popular singer?
highway 61 revisited

Mr Barkis, Edward Murdstone and Tommy Traddles are all characters in which Charles Dickens novel?
charles dickens

The word deltiologist, derived from the Greek 'deltos' meaning writing-tablet, refers to a collector of what?

deltiology